How to clear History Content in a Group Chat?

Hi,

we are using OpenFire (3.10.2) only with the Group Chat functionality. We save the conversations, thats ok, but how can i clear a chat room discussion,

because i need a new start, only for better clear view? Is it possible, to do this as Administrator for all members in a group?

Thats should work independent from the Chat-Client.

Until now it works only with a restart from the OpenFire service.

Sorry for my bad english,

Thanks in advance

Rainer