SSH key change is very easy. you just need to change the authorized_keys from the live server.
SSH key generate
at first, you would have to create a key on your local computer using GitBush. Remember it is not your live server. it would be creating our own computer that you use. after creating the key then we will transfer the key to the live server. Let’s start…
ssh-keygen -t rsa -b 4096
//comment: click 2 time for skip file location and passpharase. 
SSH key change from the server
Now we change the ssh key. let’s follow the process that I showed a screenshot.
cd .ssh
nano authorized_keys
Now enjoy the new ssh key authentication