In SQL 2014 or earlier, Reporting Services
In Reporting Services, navigate to the folder you want to change permissions for.
Click Folder settings.
Go to the Security tab.
Click Edit on an existing row in the list to change the user or group's level or access.
Tick the box next to the row and click Delete to remove permissions from a user or group.
To add a new user to a group, click New Role Assignment.
In SQL 2016 or later, Reporting Services.
In Reporting Services, navigate to the folder you want to change permissions for.
Click Manage folder.
Go to the Security tab.
Click Edit on an existing row in the list to change the user or group's level or access.
Tick the box next to the row and click Delete to remove permissions from a user or group.
To add a new user to a group, click Add group or user.