How to move mdf file to other disk drive when it is "Standby / Read-Only" mode?

I am trying to change the location of mdf and ldf file from one disk drive to other disk drive due to storage limit. Currently, the database that I am trying to move to other drive is in "Standby / Read-Only" mode. But, my understanding is that, in order move mdf file and attach database, I need to change the mode to "regular" before moving. Also, my understanding is that if I change the mode from "Standby / Read-Only" mode to something else, I cannot go back to restoring without restoring the backups again. How do I go about doing it (attaching the "Standby / Read-Only" database after detaching)?