Occam's Razor is not a valid proof technique and involves a subjective judgment call. It is a way to move forward under uncertain conditions that has a pretty good track record though. One if it main strengths is that usually simpler constructs survive better and hence are more prevalent. In science and technology, it matches well with the golden rule of constructing anything, namely KISS.
There are some areas where it seems to fail catastrophically though. For example, in Physics, both Quantum Mechanics and Relativity are not consistent with it, or it is unclear what it would advocate. (To make matters worse, Quantum Mechanics and Relativity are also not consistent with each other, i.e. they cannot both be true unless Physics is even more fundamentally wrong.) Now, Occam's Razor would probably suggest here that somebody is messing with us and that makes the simulation scenario or the presence of a god that does it a likely scenario. On the other hand, there is really no good other evidence for those models.
In reality, Occam's Razor probably works best when amended to say "Prefer the most simple explanation, unless you have good indications it is way off, and move to more complex explanations when validation of the most simple one fails. Also make very sure you understand complexity and do that validation carefully."