Within the Remediation tab of Microsoft Entra Permissions Management, the Permissions subtab allows you to view, filter, and manage the permissions directly assigned to identities. It supports operations such as Read, Update, and Delete on granted permissions.
If you need to change a user's permissions (for example, reduce all of User1's permissions to read-only), the quick action capability in the Permissions subtab is the most efficient method. Using the quick action, you can right-size, remove, or adjust permissions for a user in bulk across their assigned permissions. This is less administrative effort than creating new roles or templates The Roles/Policies subtab (option A) deals with role definitions (CRUD operations), not directly editing a given user's permissions.
The My Requests subtab (option B) is for requesting elevated permissions, not for bulk modifying existing assignments.
The Role/Policy Template tab (option D) is for defining templates; using them is less direct and more overhead when you already have assignments to adjust.
Hence, the correct and minimal-effort choice is to use the quick action in the Permissions subtab of the Remediation tab to change User1's permissions to read-only.