Along with what @StephenH wrote, check your battery.  Low voltage can induce beeping!  Don't ask me how I know.

Hello Annie,

Please go to your other two posts and delete them. You only need one posting. It will either be under Post Options or Topic Options.

Now, to answer your question. Depending on the age of the CO detector, it may be at end of life. The only proper way to silence it is to replace it with a new unit. You may be able to temporarily silence it by pressing the button, but it is temporary at best. If the unit is less than 5 years old, then the beeping may be an indicator of carbon monoxide or LP gas. In which case, you need to get out of there and get it fixed ASAP.

If it is 5 years old, then it has reached end of life. If you do not feel comfortable doing it yourself, you will need to take it to an RV repair place to get it replaced. In reality, it is quite simple. The new 5 year period will start when it is first activated.