1. From Setup, enter Permission Sets in the Quick Find box, then select Permission Sets.
2. Select a permission set, or create one.
3. On the permission set overview page, click CustomPermissions.
4. Click Edit.
5. To enable custom permissions, select them from the Available Custom Permissions list and then click Add. To remove custom permissions from the permission set, select them from the Enabled Custom Permissions list and then click Remove.
6. Click Save.