I have procured the Mikrotik server from a VPS provider company and after a long time I have changed it from version 6 to 7 but I found that the operations and commands on the server have encountered problems and now I want to upgrade it to I will restore version 6, but the VPS provider company says that they should reinstall the server and the information inside it will be deleted
Is there a way to revert to version 6?

Yes just download .npk package from mikrotik.com
Use winbox to upload it to Mikrotik VPS instance.
GO to System > Package and then click Downgrade

Maybe you will have any small changes in config, if yes just open from console that cloud provider offer and fix them!

I've done this and I'm having trouble connecting, so I've created a new post for it, which I'm waiting for the moderators to approve.