If the action achieves Congress notification threshold, then yes.
But congress may not want to do anything, so even pretty significant actions might get recategorized. He has already gone after mark kelly about telling generals to refuse unlawful orders.
American troops would be bringing in every available airlift and sealift capability, pack up everything, and leave. That's the most likely scenario.
I imagine some older heavy land equipment will be left there. High value, mobile stuff will come back. There might be a fire sale.
If you're Poland, and the Americans are leaving, Afghanistan style, the EU NATO states want you to support them and complain about Greenland, but the US offers 200 M1A2 tanks for nearly free, 155m guns, MRAPs and some older F-16, but you get nothing if you complain about Greenland. What would you do? Poland needs those tanks. They have already purchased everything they could off the open market. The idea is that Polish people man those systems, replacing Americans. high value, mobile systems, would be sold at market rate, but there would be a lot of free stuff. The US could move other stuff, from other non-complying EU countries. Heck, Poland may be able to hire some of those soldiers as advisors to help them out.
Now look up and down the curtain and see who would refuse a deal like that, to keep the important Danish holding of Greenland. If you are facing an existential threat like Poland is, it wouldn't be a debate. You would see a huge movement of ex-US material to the front lines. Germany would be deserted. Germany would likely be asked to pay for the manning of these systems in many of those countries. The stuff being in Germany is a product of the cold war, and that it could have moved further east as EU member states were bought onboard.
This would clear out a lot of US inventory, create cash, allow the US to spend a whole lot more on new stuff. It would allow it to significantly downsize its army long term, 100,000s+. Forces Europe to take the burden. Even if a lot of it gets moved to Korea/Japan/sold to Taiwan.
I think it will be more chaotic than that. But possibly likely outcomes. If I was an eastern European country, I would want a complete inventory of US equipment in Germany ASAP, and running by my defence people and say "what can we man now, what do we need? If the americans left".
Americans may keep one or two airbases for bombers. Most of the navy bases. EU-NATO will just have to accept that. That would mean at least some level of US engagement in Europe security, and capabilities Europe is weak in like air/sea power. US still wants to be able to defend itself from afar.
Realistically such an arrangement could have happened after the fall of the Berlin wall, or the Collapse of the Soviets. Its not an impossible, or improbable situation. Its been theorised for decades.