Plim,
If you are just wanting to get rid of it then follow TheQueen's advice to use the reprogram feature code [Default: 397] and then press the button you want to delete and then press Hold to erase each digit.
If you just want to change it to something else then you would use the reprogram feature code [Default: 397] and then press the button you want to change and just start typing in the new extension.
If you want that button to be a personal speed dial, let's say your home number, then here are some instructions for that.
Programming the personal speed dial:
1. Dial the program personal speed dial feature code [Default: 383]
2. Select a bin [0 thru 9] <-- Remember what number you used here
3. Type in the name for Home using the keypad [press 4 twice, press 6 seven times, press the transfer button to move forward, press 6 five times, press 3 six times]
4. Always start these with the outbound dialing feature code [Default: 8] then dial the number as you normally would to call it and press # to accept it
Programming the PKM/DSS/BLF button:
1. If the button you want to use is empty then press it and go to step 3
2. If the button is used dial the reprogram feature code [Default: 397] and then press the button you want to use
3. Dial Personal speed dial feature code [Default: 382]
4. Press the digit associated with the Bin [0 thru 9] from step 2 on Programming the personal speed dial above
The button on a 53xx series phone should now show Home and when you press that button it should automatically call the number without you doing anything else.
Thanks,
TE