I forget my memory card pasword. how can i remove it ?

My Dear:
You can recover the password, the best way is to download a file manager to your phone. I use Best Fileman from http://www.smartphoneware.com/ It's for series 60, your phone is series 40. The trial version should be enough, it's only £5.60 anyway.
In the file manager you'll find under- C:\System\mmcstore -the file you're looking for, you have to rename the file- mmcstore.txt -then send it to another mobile or your PC via bluetooth (best way) open it on the other phone and your password will be revealed.
Rename the file- mmcstore.txt -to just- mmcstore -there might be another file named- mmcstore.txt -to view your password rename one or the other- mmcstore1.txt -one is for your phone PIN number the other your MMC card.

OR:
formatting is best for ur mobile momery card
bcoz when you delete something that is not erased thoroughly.
it can be experienced by using tuneup utilities in computers.
so formatting is necessary, so use these steps
*#7370# for reset settings
*#7780# for soft formatting
if you want complete format turn off phone,charge fully. then press green button, * button, no. 3 button, lastly I/O(power)button simultaneously.
your phone will be formatted in 3 mins approx.
Enter Default lock code is 12345.