There are a few different ways to delete songs off your player.
Preventive Medicine: To prevent Windows Media Player from adding all of your My Documents files to the Sansa player every time you connect the Sansa to the computer - Connect your Sansa player to the computer and open Windows Media Player. Click on the Sync tab. Pull down the drop down menu underneath the Sync tab by moving your cursor over the Sync tab and left clicking on the little black arrow underneath the Sync tab. Highlight "Sansa 1GB" (wording may vary slightly), and then select "Set up Sync". When a window pops up, uncheck the box that says "Sync device automatically".
Quick Method 1 - Erases Everything: Connect your Sansa player to the computer and open Windows Media Player. Click on the Sync tab. Pull down the drop down menu underneath the Sync tab by moving your cursor over the Sync tab and left clicking on the little black arrow underneath the Sync tab. Highlight "Sansa 1GB" (wording may vary slightly), and then select "Format." - this should erase everything.
Quick Method 2 - Erases Everything: Get the latest firmware upgrade from Sansa - it updates the firmware and erases every song in the player all at once. Note: this method doesn't work if already have the latest firmware. Go to this website and click "Firmware Updater" to find out: http://www.sandisk.com/Retail/DriverDownloads.aspx
Slow Method, allows more control over what gets deleted: In Windows Media Player 11, the files are organized by Music, Pictures, Videos, Etc. First, you will want to plug the Sansa player into the computer. Then click the Library tab in Windows Media Player. You will most likely be in Music view. You will see two sets of folders in the left-hand side of Windows Media Player. The first set are all the files stored in your computer. The second set of folders underneath the line that says Sansa 1GB Mp3 player (I forget the exact wording) has all the files that are stored in your Sansa player. Click on the "All Songs" folder. You can individually delete all the songs that you want by left-clicking once on the song name in the middle of the Windows Media Player window, and then pressing "Delete" on your computer's keyboard. You will have to repeat this process again for images, videos, etc by clicking the little arrow next to the picture of the musical note on the upper left hand corner of Windows Media Player, and expanding the dropdown menu, and selecting "images"...then "Videos" etc.
NOTE: After plugging in your Sansa player, if you see a message that says "Connect a Device" in the Sync tab on Windows Media Player, then the cmputer is not properly recognizing your Sansa player, and you may need additional instructions from me.
-Tha Mp3 Doctor