Of course you can, just go to your account on your own computer and log out.
Once logged out, your mother will only see the log on page.
I`m almost certain but you`ve got me thinking now, just going to text my daughter and ask her to log into my mail on her laptop, then I`ll log out on mine and let you know how it goes.
Daughter logged in, then I logged out, she couldn`t get back in without user name and password even when I logged back in.
yes , log onto your account from the other comp and follow instructions
Best way I can think of is to CHANGE YOUR PASSWORD to your email account.
By changing your password, the saved password that is on your mother's computer won't work anymore so she shouldn't be able to log back in.
Hope that helps.