Yes. You can change members' permissions at any point.
How to Change Member's Permissions / Remove Members
- Open the Boards app, enter your board and tap on the share icon +👤
- Tap the 3 dots
- Tap View Members
- Tap on the email you want to change permissions
- Change permission or remove from the board
- Get a confirmation message 👌🏼
Check out this article (iOS/Android/Desktop) to learn how to do it.