Decommissioning

To take out of service or to render unusable.

"The Army decommissioned the Sherman tank by filling the turret with cement."

To remove or revoke a commission.

"After his arrest, the officer was decommissioned from the police force."

To remove or revoke a formal designation.

"The state highway was decommissioned and reverted to local control."

The act by which something is decommissioned.