Usually yes. German telecom law provides a special termination route when you move abroad and the service cannot follow you.
The route (§ 60 TKG) gives one month's notice where the provider does not offer the service at your new home, effective on the day you move out or a later day you choose. Deutsche Telekom explicitly names military transfer orders as accepted proof. Other providers vary in what they ask for, and some are more difficult than others.
Only the page of your orders that proves your departure date is ever needed. Nobody needs to see the rest.
Find the page with your report-no-later-than or detachment date.
Black out everything else.
Submit it with your cancellation and ask for written confirmation of the end date.
§ 60 (2) TKG. General information about German law, not advice on an individual case.
Usually yes. German telecom law provides a special termination route when you move abroad and the service cannot follow you.