Individual based simulation approach has attracted more and more interest in biofilm simulation. Different from the conventional biomass based simulation method, detachments are not available in many individual based simulation packages. In this paper, three detachment mechanisms were successfully integrated into an individual-based modeling package (iDynoMiCs). With the new capabilities, the influence of bacterial detachment on Pseudomonas aeruginosa biofilm was studied. The simulated results agreed well with previous reports, including the effect of shear detachment on smoothening biofilms, nutrient-limited detachment on hollowing the biofilms, and erosion detachment on isolating bacterial clusters. New findings were also discovered including the effects of different detachment mechanisms on the equilibrium state, time-dependent effects of each detachment mechanism on biofilm structure, sensitivity of the detachment coefficient values, etc.