Startup funds and lab space when leaving tenure-track faculty position
I left my former R1 for another university last year. Like you, I had research funds and two labs. I'm in the social sciences so your mileage may vary.

I spent down my research funds as much as possible. In the last months, I asked all my grad students what books and equipment they wanted and bought them whatever they needed. I tried to reimburse their conference travel where I could.  I'm pleased that I left with just a small balance remaining.

I did not give instructions to the disposal of my labs. They both reverted back to the department which I'm sure has its own plans, but I thought it best for my own mental health not to try to dictate what would happen to them -- and I haven't inquired since I left. That path would just lead to frustration and tears. But I was in full control of the lab until the very last day they were in operation.

If you're a PI on a grant, you could ask the agency either to: 1) let you transfer to the new university; 2) assign a new PI or co-PI at the old university to take over the grant; or, 3) terminate the grant if neither are possible.