1998 Buick Century Owner's Manual - Page 249

Wheel Covers To remove a center cap, use the wrench to pry gently at the notch. Don't use a tool that is narrower than the wrench to pry at this notch. Then pry off the cap. They won't come off. You will only be able to loosen them. Once you have loosened the plastic nut caps with the wheel wrench, if needed, you can finish loosening them with your fingers. Then, using the flat end of the wheel wrench, pry along the edge of the wheel cover until it comes off. Be careful; the edge may be sharp. Don't try to remove the cover with your bare hands. If your vehicle is equipped with wheel covers, be sure to use a wheel wrench to begin the process of loosening the plastic wheel nut caps.