It is difficult if your phone is bugged with FlexiSpy. On Android phone, you can install Symantec Norton Mobile Security which claims to be able to remove the spyware.
There is another popular mobile spy software called SpyMobile.
They support virtually any mobile OS - iPhone, Blackberry, Android, Windows Mobile and Symbian - which means they can be installed on almost any device.If this application is installed on your mobile phone, it is running in silent mode so there is no way to know whether your phone is bugged. However, this software should be somehow manually installed and initially configured on your phone, and there are "secret" default keystroke sequences that should be keyed in order to activate the management console. To check if SpyMobile is installed on your phone, you need to try these sequences. If nothing happens, you are lucky. If you see the SpyMobile login screen, you are not.
Windows Mobile and Symbian: #123456789*
Symantec Norton Mobile Security:
Mobile spyware review:
More information on signs of bugged phone: