WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Prying Crankshaft Rear Oil Seal With Screwdriver
Courtesy of GENERAL MOTORS CORP.
IMPORTANT:
Do not damage the crankshaft or the crankshaft rear oil seal housing.
Pry the crankshaft rear oil seal out with a screwdriver.