I have unbolted the oil pan from my 1998 Buick Regal GS and cannot get it out of the frame. I have removed the oil filter, but that does not seem to work either. Please help.

I have unbolted the oil pan from my 1998 Buick Regal GS and cannot get it out of the frame. I have removed the oil filter, but that does not seem to work either. Please help.

Removing the oil pan is a major project on these cars and it requires some special tools.
What exactly are you trying to access?

There "might" be an easier way but here are the official steps for this procedure on a 1998 Buick Regal. This information should be accurate but make sure it fits your application.
For example, you have the GS model so you will also have supercharger components to consider.

I recommend getting the factory service manuals which have more detailed instructions and photographs.

Oil Pan Replacement: 1998 Buick Regal and Century
Tools required:
J 28467-B Universal Engine Support Fixture
J 28467-90A Engine Support Adapters
J 36462-A Engine Support Adapter Leg Set

Disconnect the battery negative cable.
Disconnect the throttle body air inlet duct.
Remove both upper engine mount struts from the engine.
Remove the drive belt.
Install all three engine support fixtures.
Raise and suitably support the vehicle.
Disconnect the three-way catalytic converter pipe from the right exhaust manifold.
Remove the right front tire and wheel.
Remove the right engine splash shield.
Drain the engine oil.
Remove the oil filter.
Remove the AC compressor bracket bolts.
Reposition and secure the AC compressor.
Disconnect the power steering oil cooler pipe brackets from the frame.
Remove the engine mount bracket bolts.
Remove the engine mount lower nuts.
Remove the torque converter cover.
Disconnect the oil level sensor wiring harness connector.
Remove the oil level sensor located in the oil pan before removing the pan to avoid sensor damage.
Lower the vehicle.
Use the engine support fixture to raise the engine.
Raise and suitably support the vehicle.
Support the frame and loosen the left side frame bolts.
Remove the right side frame bolts.
Lower the frame for access.
Remove the engine mount and the engine mount bracket.
Remove the oil pan retaining bolts.
Lower the oil pan.
Remove the oil pan.