Hi
To solve your problem , you could only delete the deployment and create a new one set to "required" instead, this is by design.
Here is a similar case we could refer to
Change deployment method from Available to Required
https://social.technet.microsoft.com/Forums/en-US/6b5f916a-c805-436e-983b-6a9ecf1854a5/change-deployment-method-from-available-to-required
Best Regards
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