Please note removing the permission may also result in losing access to create other forms. We wanted to remove the button however our users do not have access to create PMGM forms hence the button does not do anything even it appears in the PMGM inbox. We have managers who have access to create other forms such as offer etc which works on the same permission - General user permissions-Permission to create forms.
This button is controlled by the following RBP: General User Permission --> Permission to Create Forms. Removing this permission would also remove the button from the Performance Inbox.
Please note - I would not recommend removing it from Admin users since it would also prevent them to use the Launch Forms tool.