Step 1:
Click「Settings」,click Team panel
Step 2:
At the Member List find the team member that you would like to restrict
Step 3:
Click on the team member’s name and look through the restrictions
Step 4:
Find Chat Access and disable the restrictions
Note : if the Green Tick at the side is uncheck means the restriction is turned on
Step 4:
Look for the Message access and uncheck the restrictions as well
Note : if the Green Tick at the side is uncheck means the restriction is turned on