If you want to end the PMS connection between Sirvoy and Myallocator and downgrade to Sirvoy Premium this is the steps to take:
1) Before you are able to downgrade to Premium you need to first disable the PMS connection to Sirvoy in the Myallocator account:
Log in to Myallocator. Go to "Status > PMS Connections"
Go to "Active Connections > PMS > Sirvoy > Disable"
Confirm that you want to disable the connection to "PMS Sirvoy"
2) When you have disabled the PMS connection exactly as above you need to confirm this to Sirvoy support for them to deactivate the Sirvoy connection to Myallocator.
3) When Sirvoy has confirmed Myallocator is disconnected you will be able to change Sirvoy version from Deluxe to Premium under "Settings > Your account" in Sirvoy.