Hi, I keep getting this message asking me to "Sign In to iMessage" everytime I boot up. How do I stop it?

Hello,

I have a feeling this might be due to me having followed iPhone's instructions to enter my AppleID after I bought another iPhone..it asked me to enter my Macbook Pro's password, and I did. However, once I knew it was for using iCloud (which I choose not to use) I reset the iPhone and started it over without entering my AppleID.

Now, I keep getting this message to "sign in to iMessage" (which I also don't use.)

Is there a way to stop getting this message each time I power on my laptop?

Thank you!