Here's a way to be able to donate/give blood in order to get Hemoglobin down that a lot of people don't realize.
Places like the Red Cross, blood banks, and donation drives, they are set up for people to donate blood for them to be able to use, as in to supply blood banks for for people that need blood transfusion.
So, if the blood isn't usable, for whatever reason, then that isn't part of what they're there for. Sometimes people that get rejected can take it the wrong way, but it isn't that they are just against helping you out, its that they have some laws that dictate what they can and can't do in different circumstances.
If anyone runs into that, what you need to do is get a prescription for a blood draw and disposal from your physician, and most physicians can tell you where to go in your area for it - and then they will be able to draw your blood and dispose of it.
I hope that makes sense and helps anyone that may run into this.
As part of my endocrinology condition, my hemoglobin has run high at times when they had tried me on certain things, and I'd ran into that and that's how I learned about it. I used to think I could just go give blood, and it initially bothered me when I was rejected bc of it, but once I found out the full story and understood the why part, it made sense.