Hello @Amir_Kian, welcome to the community forum.
As @ADA4Good has kindly replied it is not possible for anyone to access your key through the Yoroi extension -whether you removed the extension or it is still installed. This is impossible even for yourself -once Yoroi shows you the mnemonic the first time, it will never show it again- so it is your responsibility to make a note of it.
These words can be easily verified by following the instructions shown in the image below. As you can see - and personally check in your browser - the key itself is never saved on the computer, but is encrypted with your spending password before being saved. This is great news, but note that it also means that the simpler the spending password you set, the weaker the security with which your key is stored.
If you would like to verify how secure the encryption method used by Yoroi to store your key is, and how unlikely it is for an attacker to find your passphrase using a brute force attack, please read this article:
BIP39 brute-force complexity (or how hard it is to break someone’s secret words)