How do I clear the memory for a Brothers lc61 fax machine

Most likely the memory is full because your fax machine either can't print what is in the memory (check paper, ink, etc), or it can't send out faxes you've already scanned into it. (check phone line and ability to dial).
To clear the memory, unplug fax from phone and wall, wait 30 seconds, and plug back in.

yes you must remove the plastic strip before inserting the cartriges other wise the ink cant cover the head or jet

The Brother faxes have a button that you can press to allow you to dial without picking up the phone. Look for a button labeled "Hook." Pressing it should hang up the machine.
If the Hook button doesn't make a difference, unplug the phone line from the machine, partly to make sure it's your fax that you hear, and partly because if you leave it connected and "off hook" the phone company will disconnect you from their network.
Three things that might help if the Hook button doesn't help are:
1. Unplug the power and plug it back in after about 5 seconds.
2. Clear the memory. You need to enter Maintenance Mode for this. You didn't give us a model number, but newer machines use this routine:
Menu
Black Start
Up-arrow
Up-arrow
Up-arrow
Up-arrow

Do the above quickly, ignoring any error beeps. If you're successful, all the lights will flash in unison, and the display will read, "MAINTENANCE." If not, touch the Stop key and try it again.
Enter the number 91: just touch 9, then 1, and wait while the machine clears it's memory. It will not clear your name and phone numbers from memory.
Enter 99 to exit Maintenance Mode, and wait while it goes through it's complete startup.

Plug the phone line in again and see if that dial tone is still there. If so, unplug the phone line again and try exactly the same routine, except that instead of entering 91, enter 01. That will clear all of your memory, as if the machine is fresh out of the box.

3. If clearing the memory doesn't help, you have a bad main board in the fax. If it's under warranty (1 year in the US), Brother will cover all parts & labor. If not, it may not be worth the cost to fix it.

turn off the sound on the brothers machine... and set the fax to memory fax...

I’m happy to assist further over the phone at https://www.6ya.com/expert/norman_d2fa496dce30c65d

with this model, power the Brother fax machine off with the power button, then, while holding down the Stop button, power the fax machine back on. Keep the stop button held down for a few seconds. That should clear the jobs resident in memory.

Do you have faxes in memory? You may need to either erase faxes in memory or print them out.
Printing a Fax in Memory
If you have Fax Storage ON for remote retrieval, you can still print a fax in the
memory when you are at your machine:
1 Press Function/Set, 8, 4.
2 Press Start.
3 Press Stop.
(See Turning On Fax Storage, page R-2.)

You have memory lock up. to ram clear the machine we need to clear out all memory. ( like it came out if the box )
1. have machine turned on
2. press 8,*,9,#.7 ( this will git you in to the programing of the fax )
3. press start
4. press the # key till memory clear
5. press start !( will clear out all memory )
it should print out a memory clear report
6 press stop key 2 times now lets se how it worked
let me know
good luck

try calling brother tech support  1-908-704-1700 good luck brother tech

see the user manual

set to manual answer, user guide available at
http://solutions.brother.com/index-asia.html