To edit or add a welcome message on CentOS (and this will probably work on other Linux distributions too), simply login to SSH first.
Once logged in, edit the following file /etc/motd with vi, nano or any other editor you prefer. I like nano, so I’ll go with that.
Here, you can customize the message or, maybe, even simply remove it if it annoys you.
However, if you don’t find the welcome text in /etc/motd, you can simply search for it. If the welcome message contains ‘Hello there’, do the following to discover which file it is in.
cd /etc && grep "hello there" *
This command will first change the directory to /etc and then perform a search for the query you enter. My welcome message was in /etc/issue.
Now logout and login again to see your artwork! I’m sure proud of mine.