In this study, we present a theoretical and numeric analysis of an untethered microrobot manipulation technique that can be used in a liquid environment. A microrobot, which is levitated on a pyrolytic graphite surface, allows us to achieve high precision positioning (at nano level) and control with lower external magnetic force requirements due to stabilizing manner of its locomotion. Stabilizing microrobot is controlled via a single "lifter magnet" as a driving force that is placed on an automatic micro-stage in order to provide stable-motion about x, y and z axes. The presented microrobot is designed for single cell manipulation and transportation operations in liquid medium. It can be used in different experimental setups such as lab-on-a-chips, petri dishes. Here, a new approach to determine an optimal experimental setup of the diamagnetically levitated microrobot, which provides the most effective and possible microrobot control, is explained with FEM (Finite Element Method) analysis and required background information. For such untethered microrobot control experiments in a FEM program, determination of the size of materials used, selection criteria, required magnetic force effects, and optimum pyrolytic graphite sizes are discussed in detail. To do that, our proposed analysis method suggests how to construct such an FEM model parametrically in COMSOL (R). Before starting the experimental work, the effects of the material and dimensions of each element forming the system on the microrobot are discussed in detail. Moreover, the manipulation technique which revealed the theoretical infrastructure is compared with the numerical calculations and the results are shown to be compatible with each other.