Hi!
I needed to clear my samsung sch-u740 of my cell number in there. COULDNT FIND any answers for that particular model- so I called verizon up and after speaking to three techs they were able to help me. So here it is for anyone who needs it, as it isnt the same for all models of this phone...
flip phone in portrait mode only
click MENU
go to settings and tools
hit *
KEY 000000
GO TO NETWROK SETTINGS
CLEAR YOUR OLD NUMBER OUT BY PRESSING CLEAR or delete
then replace those deleted numbers with ten zero's 0000000000
hit OK
then scroll to NMSID (WHICH IS LINE 3)
check to see that new phone number in there is 0000000000 (ten zero's)
then hit EXIT
PHONE SHUTS OFF AND RESETS with YOUR OLD CELL NUMBER CLEARED
and replaced by zero's.. now that you have done that and cleared your other contacts and pix and videos and whatever you had stored by doing phone reset--- your phone is ready to go to someone else!