Cisco 4700 deleted username

We have an employee who recently left our employment, shartly there after we tried to log into our 4700 router. Trying to log in with our normal username we received a % Login invalid. We did a little research on his last telnet session and it lookslike he removed the line “username ????? password ?????” from our configuration files and yes it looks like he wrote the running config to memory. Now we have no way (that we know of) to login. We tried to plug into the cosole port but could not find an RJ-45 port. Our current IOS is 11.1 and router is a 4700. Could anyone tell us if there is anyway to fix our problem.

Thank you.