When an A320 flight crew wrote up the green system hydraulic quantity as above the max refill level during their walkaround they were asked by Maintenance Control to modify the report to 'entered in error.' The flight crew refused to do so. In addition; a Contract Mechanic was allowed to circumvent established safety practices regarding operation of the hydraulic system without an external monitor to insure no injury resulted when doing so.

Narrative

During the preflight the green hydraulic system quantity was above maximum refill. Maintenance Control was contacted through Dispatch and; in turn; called out Contract Maintenance. Contract Maintenance understood the write up and was in agreement with flight crew as to the necessary maintenance action to take. Maintenance Control; however; asked the Captain to change the discrepancy write-up to 'entered in error.' The Captain preferred not to change the original write-up as; in his opinion; it would have been inaccurate.While the right main landing gear door was still open; the Contract Mechanic; standing in the forward galley; was on the phone with Maintenance Control and asked the Captain to pressurize the hydraulics. The Captain preferred not to comply as it was unsafe without clearing the area first. The Contract Mechanic then pressurized the hydraulic system without clearing the area. The flight crew remained clear of the flight deck while maintenance was being performed.Maintenance and Contract Maintenance personnel did not follow SOP; they must be retrained to not ask flight crew to change maintenance discrepancy write-ups to 'entered in error' when; in fact; a discrepancy exists and; also; to require contract mechanics to perform their duties with strict adherence to established safety protocols.