A: I don't remember much, though.
B: Just try to give me as much details as you can remember.
I feel like something is wrong in B's sentence. I've never heard people say something like this.
The issue here is the use of many vs. much. Typically, many modifies countable nouns, while much modifies uncountable ones. Reference
With "details," a countable noun, the proper sentence would be: "Try to give me as many details as you can remember."
But you could also have "detail" used as an uncountable noun like "information": "Try to give me as much detail as you can remember."
It's the combination of much and details (plural) that doesn't work.
You should use one of the following:
As much detail.
As many details.
Detail, as a mass noun, takes a singular form—which much is used with. (As much water or as much candy.) And details, as a countable noun, is plural—which many is used with (as many drinks or as many chocolates).