If you’re viewing the other person’s screen: Choose Screen Sharing > Quit Screen Sharing.
Tip: Don’t want someone to send you screen-sharing invitations? When you receive an invitation from them, hold the pointer over the Decline button, click menu bar, then choose “Allow [name] to control my screen” so there’s a tick next to it.
To take back control of your screen — but still let the other person view it — click in the menu bar, then choose “Allow [name] to control my screen” to remove the tick.
If you donʼt give someone screen control, they can still click to highlight areas on your screen.