I have two Gitlab accounts. On my old account I added an ssh-key that is located in ~/.ssh/id_rsa.pub on my computer.
Generate SSH please follow below steps.
Open Git Bash on you machine

Enter the below command to genarate
ssh-keygen -t rsa -b 4096 -C "yourmail@example.com"
Generating public/private rsa key pair. Enter a file in which to save the key (/c/Users/you/.ssh/id_rsa):Press enter Enter passphrase (empty for no passphrase): Type a passphrase Enter same passphrase again: Type passphrase again
Once enter the confirm passphrase, will get confirmation message.

go to the gitpair.pub file location and right click open with notepad. copy the code and past the in the below text box, your email will pick automatically in the title box. then click add key.
