How can i remove a device from my authorised devices on apple account?

To remove a single device, you must deauthorize it using the device. In other words, you cannot deauthorize a particular iPhone from a computer.

However, you can use iTunes to deauthorize all your devices at once. Go to iTunes, click your account, sign in, and click the "deauthorize all" button. This is useful in the event a device becomes lost, broken, or otherwise inaccessible.

After that, simply authorize each device individually.

Beware that you can only "deauthorize all" once a year.

Ah...you don't authorize/deauthorize devices at all...ONLY COMPUTERS.

Authorization applies ONLY to computers.

ipods/ipad/iphones , Apple tvs are NOT authorized at all.

Dr mizooo_1985 wrote:

And im asking if any one who use this pc can see my backup data or not?

Did you erase the drive before getting rid of the computer? If so, no. If you didn't, well...yes.

Dr mizooo_1985 wrote:

And i didn' erase anything,

Hope her new BF is not a forensics expert 😎.

Can she see my icloud-backups???

Not unless she knows your Apple ID/Password...or her new BF is good at forensics.

What can i do to prevent icloud-backup to this pc???

Same as my last answer...good luck.

Yep. But change your password anyway...at LEAST 9 characters...combination of upper/lower case & numbers...completely random...nothing that can be guessed.