How to disable Messages app?

On my work computer, Messages pops up every few hours asking me for my password. I have never used Messages on this computer and nor do I want to. It is my WORK computer and should not be receiving my personal text messages for privacy and security concerns.

If I start Messages on the computer it immediately asks me to log in and won't let me change any settings unless I do. How can I disable it or delete it so it stops popping up a message randomly several times a day asking me to log in. Again, this is a work computer and under no circumstances should be receiving messages.