In order to unistall RealPlayer 8 for Mac OS you need

Step 1. To run  the g2cln uninstall utility (located in System Folder; Extensions; Real). This utility completely removes all files for RealNetworks products. You must reinstall any RealNetworks products you had previously installed after using g2cln. After running g2cln, perform the following clean-up steps

Step 2.  Open the System folder; Extensions folder; Real folder. If the RealPlayer folder exists, drag it to the trash.

Step 3. Open the System folder; Application Support folder. If the Real folder exists, drag it to the trash.

Step 4. Open the System folder; Extensions folder. Drag the Real folder to the trash. If there is a RealAudio folder here, drag it to the trash as well.

Step 5. Open the System folder; Preferences folder. Drag all Real Preferences to the trash.

Step 6. Restart the Macintosh, Empty the Trash, and Reinstall RealPlayer if needed.