1How do I remove small pieces of aluminum foil which are stuck to the bottom of my oven? 2 If I can't remove the small amounts of alum. foil, Will still be able to use the self-cleaning feature?

It says right in the owner's manual not to use aluminum foil on the bottom of the oven. Try to remove it with steel wool...

I would try a copper scouring pad.
Aluminium is very soft - Mohs hardness of 2.75
Copper has a Mohs hardness of 3, just slightly harder.
https://en.wikipedia.org/wiki/Hardnesses_of_the_elements_(data_page)
Ceramic tile has a hardness of 7
Mohs Hardness Scale

This means the copper scouring pad should be able to remove the melted foil without scratching the ceramic - but test first to be sure.

How would I remove aluminum foil stuck to the bottom of a convection oven?

With the older models of self-cleaning ovens one could put aluminum foil on the bottom tray of the oven, but with the newer models there is a warning (hidden in the last line) of your booklet for models of stoves where aluminum foil should 'not' be used! Even though print in small and many consumers are complaining regarding their stoves and melted aluminum stuck to the bottom tray of their oven (nothing will get it off) all manufacturer do 'not' cover this problem under warranty and thus, it will cost you money to buy a new tray. You unscrew the two screws to the bottom of the damaged tray of your oven and then install the new one and put back the screws. Letters of complaint should be written to the manufacturers to have them put this warning in clear bold print right on the front cover of the instruction brochure.

Don't use self clean. Get some easy off oven cleaner. Self clean gets too hot and ruins expensive delicate electronics.

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You may be able to get it opff with the oven hot. Whatever is holding it was liquid when hot before, so should at least loosen enough for you to remove it.

If the bottom of the oven is enamelled or has a pyrolytic self cleaning surface then you can use caustic soda to remove aluminium foil.

Many oven and hob cleaners contain caustic soda and those which do always advise that it's kept away from aluminium parts precisely because of it's effectiveness in turning aluminium into grey foamy goo!

If you're in doubt as to whether your oven floor is caustic soda resistant then try a small test patch first.

Please note that caustic soda is extremely corrosive so you'll need to keep your hands and arms covered and preferably use eye protection as well.

(Wear a professional n95 mask and rubber gloves). Use a straight razor and scrape off as much foil as possible. Get a hold of Mercuric or sulfuric acid. BE CAREFUL not to spill anywhere, work close to a stainless steal sink. Poor a little in a small glass container and bring over stove porcelain surface. Pour the acid onto the foil and wait 3-4 minutes, use paper towel to wipe off the acid, and then a soapy wet rag. Repeat process until all foil is dissolved. Then wash surface thoroughly and repeatedly with a soapy dish towel. Once complete run water in the sink for 5 minutes till any possible remaining accid is flushed from the sink. The foil is gone and the porcelain is preserved. Works great! (Don't breathe the fumes and ventelate the area or move the stove outside)

have you tried warming the oven up first on low temp and then gently applying a paint scaper

mr muscle have a good degreaser but it can be strong in fumes read the tin first

Use "The Works Toilet Bowl Cleaner" to dissolve the foil. *Caution* when the cleaner is applied to the foil a chemical reaction occurs releasing some harmful fumes so please use outside or in a well ventilated area. I just did this to a Frigidaire oven I bought from Lowes at a discounted price. The previous owners bought it, did not read the owners manual or just disregarded the warnings on using foil in the oven and thought they would line the bottom pan with foil to help make it easier to clean (Good idea, but don't try it on the hidden element ovens). With the heating element being hidden under the drip pan the heat is hot enough to melt the foil and fuse it to the pan. Now most of the pans on these ovens are removable by just a couple of screws and I strongly recommend removing the pan when doing this. Squirt some Works toilet bowl cleaner on it in a well ventilated area and watch it go to work. It took about 15 minutes for it to dissolve all the foil on my oven, then I rinsed it clean and reinstalled it in the oven. The pan does have a slight discoloration on it, not from the cleaner but from the foil being melted onto the pan, if you choose you can buff this out. Most of the modern ovens have the ceramic coated drip pans in them so the Works toilet bowl cleaner will not harm them, unless you have scratched the finish off. Works Toilet bowl cleaner contains a fair amount of hydrochloric acid which is what makes this work so well.