code: boolean removePersona(SPFPersona persona) {
  		SQLiteDatabase db = getWritableDatabase();
  		if (persona.getIdentifier().equals("default")) {
  			return false;
  		}
  
  		String table = Contract.TABLE_PERSONAS;
  		String selection = Contract.COLUMN_PERSONA + " = ?";
  		String[] selectionArgs = { persona.getIdentifier() };
  		if (db.delete(table, selection, selectionArgs) > 0) {
  			deleteFieldsOf(persona, db);
  			deleteVisibilityOf(persona, db);
  		}
  		return true;
  	}
docs: Delete a SPFPersona. All the information related to the specified persona
  will be erased.
  
  @param persona
  - the {@link SPFPersona} to remove