If one of your Channel Operators has decided to “takeover” your Registered Channel, there are multiple ways to stop them.
If you are the channel Manager (access 500) or have a higher access level than the operator attempting the “takeover”, you can:
/msg X suspend #Channel Username <duration> [level]
/msg X remuser #Channel Username
You will then need to possibly UNBAN yourself with X, if you are banned. If restrictive modes are preventing you from joining, you can use X’s CLEARMODE command.