In order to program a remote without the code, you will need to reset the remote entirely and pick a new code. Usually, this involves using the reset key or the device key to erase the memory in the remote and program in a new PIN code. \
In most cases, erasing remotes from the garage door system is accomplished by pressing the learn button until the indicator light starts blinking. This will usually erase all remote codes and from there, you will have to follow the programming instructions to reprogram all of them. \