From any device currently linked to your account:
On a Desktop (Mac or Windows), click the 3 white lines in the top left to open the menu, then click Settings > Device Management.
On a mobile device like iOS or Android, tap the menu symbol, then click Settings > Device Management.
From here, you'll see a list of devices activated on your account.
From this menu you're able to click the "X" next to any device to remove it from your account.
A prompt will ask like below. Click RESET
Once you remove a device from your account, if you want to use it again, you will need to logout and then use the “Reset Your Device” option to be able to send and receive messages again.