Can I change my wordpress theme from another computer?

[Meenu]

Can I change my wordpress theme from another computer ?
without having to install wordpress
Can I change it online ?
I helped my mom created a website on wordpress last year. And I was very difficult at first for me to install things and stuff.
Now she's asking me if I can change her theme but I don't want to install anything on my computer.
Can I do that ?
(I already said "Of course, I will" but I don't know if I can do it )

[Shirshak]

At first you can change wordpress theme from any computer that has acess to internet but you need to have theme file or installed.
Yes you can change it online by going to apperence > theme from yoururl.com/wp-admin