fix bug, can not remove session file

@@ -143,7 +143,7 @@ func (fp *FileProvider) SessionExist(sid string) bool {
 
 
 // Remove all files in this save path
 // Remove all files in this save path
 func (fp *FileProvider) SessionDestroy(sid string) error {
 func (fp *FileProvider) SessionDestroy(sid string) error {
-	os.Remove(path.Join(fp.savePath))
+	os.Remove(path.Join(fp.savePath, string(sid[0]), string(sid[1]), sid))
 	return nil
 	return nil
 }
 }