The amount of space debris in the near-Earth space environment poses a major challenge for current and future space missions. Controlling the growth of on-orbit debris utilizing on-orbit debris removal missions is of great importance for sustained space operations. This paper focusses on the laser-based removal of on-orbit debris utilizing the physical process of ablation. We consider the momentum change of the debris due to laser ablation and investigate the de-orbit times for debris that has cubic and spherical shapes. Our focus is on modeling the de-orbiting process as a low-thrust transfer under the action of continuous perturbation forces. We present numerical results for a variety of starting orbits for the debris.