If you want to roll back multiple service packs applied to a version, you need to start with the latest service pack. Roll back goes to the same state before installation.

For example, if you have a 10.2.2 HotFix 1 instance where you have directly applied Service Pack 2, and you want to roll back to 10.2.2, you must roll back in the following order:

Service Pack 2
HotFix 1

Suppose you had a 10.2.2 HotFix 1 instance where you had applied Service Pack 1 followed by Service Pack 2 to finally install 10.2.2 HotFix 1 Service Pack 2. If you want to roll back to 10.2.2, you must roll back in the following order:

Service Pack 2
Service Pack 1
HotFix 1