Change encryption option from user specific to mater key

We have an instance of owncloud with encryption module enabled. The current encryption option is "user specific key" that is incompatible with some apps (like ONLYOFFICE for online editing word and excel file). These APPS support only encryption with master key. What are the steps to safe migrate encryption option from user key to master key? We have 700 GB of encrypted data

The documentation provides everything you need to decrypt your data and encrypt it with master key again.