SymbOS/SDropper.A is a broken installation of 3d minigolf game that drops SymbOS/Skulls.J files.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
F-Secure Mobile Anti-Virus for Symbian detects this malware starting from the
Detection Type: Mobile
Database: update build number 15