Making `escape Ctrl-n` switch to window n

The problem is that my terminal maps Ctrl-n, for certain values of n,
to various escape sequences.

For example,Ctrl-3 generates ^[ (escape), so it enters Copy Mode
instead of switching to window 3.

Ctrl-4 genertes \^ (FS, which is interpreted as SIGQUIT).

Etc.

Is there a way to "unmap" combinations like Ctrl-3, so they'll be
interpreted the same as just pressing 3, and not as their current
special escape meaning?

Thanks, D.