If a domain controller that holds one or more of the five FSMO roles becomes permanently unavailable, you’ll ultimately need to seize the roles to another domain controller. Seizing FSMO roles is not a graceful process and is intended only to be performed when the unexpected occurs.
In normal day-to-day operations, if you need to change what domain controller a FSMO role is held by, you should instead transfer the role. In order to seize the RID Master, PDC Emulator, or Infrastructure Master, you’ll need to be logged in as a Domain Admin. To seize the Schema Master or Domain Naming Master, you must be logged in with Schema Admin or Enterprise Admin permissions, respectively.