Is it possible to remove the overlayed effects seen in Geth hunter mode and Krogan blood rage?

Hmmm.
In my opinion I would have thought Mgamerz would be the one to know how to do it.
But if he's sending you here then maybe it can't be done?

The only possible help I can give you for the Geth characters is to spec out of Hunter Mode and equip the Geth Scanner.
Not ideal, I know.

As for Blood Rage, I have nothing

There's several methods, but the easiest one that I know of is using TexMod. I don't remember precisely where I got it from, but a Google search should help. Keep in mind, that this requires faffing around every time you run ME3 because EA Origin is a POS that likes to interfere with *everything*. However, most of the messing around can be automated through using a Batch file (When I was searching for this a while back, the text needed to make this was readily available from most places discussing it). There is a way to decompile ME3 and replace the textures for the overlays so that faffing around isn't required but it's a much more involved and complicated process that's above my skillset.

Some terms that may help you are 'ME3', 'TexMod' (Texture Modification), 'Clean HUD', and 'Hunter Mode Fix'. I'll try to remember to pop back in and see how this thread progresses, if it seems this method has disappeared from the internet, I'll see about getting the files for this back out there, however, I have only got the files for Hunter Mode, since it was by far the worst of the overlays for me, however, I can totally understand wanting to get rid of them all.

sheesh, be patient OP. give it time! once the pattern burns in into the retinas you'll stop noticing it just like the rest of us problen solved!