The Facebook app for Android is awful. 50% of the time it doesn’t upload photos properly and they are forever stuck in the notification area since there is no way to cancel them. You can clear them by restarting the phone, but that’s a pain. An easier way would be to log out of Facebook using these steps.
1. Open the Facebook app.
2. Tap the Menu button.
3. Select Logout.
4. Select Yes on the warning about removing Facebook data.
The stuck upload is now cleared from the notification bar. You can now log back into the Facebook app if you wish. The item you tried to upload will not return unless you try it again.
If this happens regularly, you may want to consider just using the Mobile Facebook site. It provides a more reliable option for uploading photos than the app.