I instal 5 fans with remote control and all fens respond to one of the remote, can I
Reset remotes to a different cod, or..

First, you should re-read the instructions that came with the fan, it will most likely say something in there about it.

I just installed a Harbor Breeze fan with a remote. The remote sensor in the fan had 4 numbers in it that you could change to any different combination, and you would put those same numbers in the corresponding remote, where the battery goes. I don't know if your fan is the same, but I would say check inside the remote and see if there is a number code pad in there. If so, then you'll have to change it in there and up in the fan.

Yes you can change the frequency of the remotes and receivers.

Ceiling fan remote controls - help and FAQ- Ceiling Fans N More