1. Go into memory mode (not VFO) scroll to your accidental memory and remember what that number is.
2. Back in VFO mode, input your freq, and hold the function key for a few seconds until it asks you where to put it in memory.
3. Scroll to the accidental memory number (in stead of placing it in a fresh spot) and press the function key again. It should say "Overwrite?", push function key once more.
Or you could reset the radio, instructions in the manual. Or you could find someone with the programming cable/software. You can't clear the memory completely, but there are instructions in the manual on how to "mask" the memory spot so it doesn't show up while in memory mode. "Masking" is essentially "skipping" your mistake memory spot while in memory mode.