Hi big dee.
Deleting songs from your M230 can be done by either browsing the player through your Windows Explorer and then selectively deleting the music file, or by formatting the player which would delete all of your music files.
It's also important to know that your player has 2 modes -- MTP and MSC -- because music files saved in one mode would not be seen in the other mode, and vice versa.
To switch the modes on your player, use the menu and navigate as follows:
Menu > Settings > USB
You would get a choice of "Autodetect" (this is for MTP) and MSC.
Here's how to delete the files:
Plug in your player to your computer. Open explorer and check if your player is detected. Your player's LCD would display "USB Connected" and the mode would be indicated below that.
If your player's mode is MTP:
A. Look for the Sansa M230 icon on Explorer (it will be recognized as a Portable Audio Device). Double left click on it to browse the player.
B. The player will have 2 sub-folders: "Data" and "Media". Double left-click on the "Media" folder and either find your music files or open the "Music" folder to find your music files
If your player's mode is MSC:
A. Look for the Sansa M230 icon and drive letter on Explorer (it will be recognized as a "Removable Drive". Double left click on it to browse the player.
B. The player will have several sub-folders such as "Audible", "Config", "Record". You may already be able to see your music files or the player may have a "Music" sub-folder. Open that to check for your files
Once you've located your files, you may now be able to delete them.
Once you've unplugged your player, the M230's LCD will display the message "Rebuilding Library". Let that process complete, then you may turn on your player to confirm that the files have been deleted.
To format your player, just right-click on the M230 icon in Explorer, then select "Format". When the Format window appears, make sure to select "FAT" as the File System type, and also make sure that the "Quick Format" checkbox at the bottom of the Window remains un-checked.
I hope this info helps. Enjoy your M230. :)