How do I remove write protection from a USB memory stick?

Memory card, flash drive ?
Either of these should work, unless the device has a slider bar to protect, in which case change the position of the bar.

Start command prompt (Run window)
Type regedit and press enter
Now the registry window will be opened.
Type the following path or copy, paste
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies
just do the Double click on Write Protect Tab and make the value as zero
Exit the regiedit window

or

Right click the drive, format, fat32 file system.