Canon NP6551 Operator's Manual page 221

Press the [STORE USER ID#] key, then press
2
the [OK] key.
Press the [CLEAR ALL ID#s] key.
3
Press the [OK] key.
4
MEMO:
●
If you want to stop all the ID#s from being cleared,
press the [C] key.
All the ID#s are cleared.
If you press the [OK] key, you will return to the
Standard mode.
MEMO:
●
Storing all the ID#s under "000000" will also clear all
the ID#s.
iii