Hope you have disable the policies and Disk set to None to remove it. But if you can elaborate a little on ""but the "Drive Encryption System Status" remains active, so no way to go further. We experience this behavior on a regular basis, with no clue to avoid it"" it will help to understand.
One thing you can try,
Create Tag - Decrypt.
Create Drive Encryption policy - Product one - Deselect Enable Option and Encryption set to None for all drive.
Create Policy Assignment Rule and assign Drive Encryption Product policy to Decrypt with tagged system Decrypt.
Create Client Task - with Encryption uninstall with Decrypt tag.
Hope this will help
Thank you for your suggestions, but what do you mean by "tag" ? Policy and task entities, ok, but tag ?
The goal is to remove the encryption, and after having deactivated the encryption, the PC is well decrypted, but the encryption statut displays "Active" (both on the ePO and on the client side), although it must be inactive prior to uninstall Drive Encryption from the client system (p35 on the McAfee Drive Encryption 7.1.0 Revision B Product guide)
In fact we have found a similar behaviour in the knowledge base (KB76103) which suggests to change a string value to force the (encryption) system state, We have applied the solution and we were abble to remove EEPC. 100% efficient, but there is something wrong somewhere as we should not have to change the registry manually.
After the registry modification it is important to not synchronize either from the PC or the ePO after changing the string value in the registry otherwise the registry string value is changed again to Yes !
Tag is criteria to identify system in ePO, it's on Menu --> Systems --> Tag criteria
I think this is due to some strings not uninstall properly from system and hence you have to perform manual steps.