Change your Samsung and Google passwords from a different devices and then re sign into your Phone with the new password you created. Once you've signed back into your device go to the website below and sign out of everything that isn't yours.
click your profile picture in the top right corner and select account - devices and sign out of everything there thats not yours.
If you've found my post to be helpful, Please like my Comments โโโ. If my response resolved your issue, please press the Like and โโโ to Accept as Solution button.
Sharing what? Your mobile connection, your wi-fi? Just generally creating havoc on your phone? In addition to what @GaryB82 mentioned, change the password and network name on your mobile hotspot (or disable it by deconfiguring it, if you don't use it.) Make sure auto-hotspot is turned off. If they are piggybacking on your wi-fi, change the network name and password, and make it a hidden network.
