Massive acknowledgements or erase of events

Hello, Let me to explain you: I have in my Scada more tan 800.000 unacknowledged events, We need to acknowledge or erase it, please could You helpme???
By my side, from the squl menú I can select and get the events but when i try to erase, The message is: “Cannot be called with a statement that return a row count”.

I hope Your support…

Thanks so much

Jorge G