Ok firstly what about you, is there a clinical reason for reducing your dose such as side effects, or do they just think estrogen is dangerous or you're too old?
Assuming you do need a lower dose, the difference between using a 75mcg patch and cutting off a sliver to approximate 62.5mcg is absolutely negligible.
A 75mcg patch will be delivering less than 75mcg estradiol anyway after the first 12 hours or so, and less than 50% of that if it is still attached after 3 days.
However if you are very keen on achieving 62.5mcg as the initial dose delivered you can simply get a ruler or just estimate it and cut one sixth of the patch off with clean, sharp scissors along one edge.
If not using adhesive dressings over the top, you may find it helpful to round the sharp corners slightly which helps stop it lifting off at the corners.
Alternatively you could wear a 50mcg patch plus half of a 25mcg, which may be easier to split precisely.
However it really, really doesn't matter clinically between 75mcg and 62.5mcg.
If that made a meaningful difference they would sell patches in smaller dose steps.