No, "anymore" should be one word here; "any more" refers to quantities (Would you like any more tea?). "Anymore" is an adverb that refers to time (I don’t like tea anymore.).
IMHO "У нас больше не будет математики." doesn't stress quantities of math lessons, but the fact that in the future they won't have math lessons ever again. (My guess is the "any more" version would be: У нас не будет больше математики.)
negative forces genitive and it's the genitive for maths ref : https://en.wiktionary.org/wiki/%D0%BC%D0%B0%D1%82%D0%B5%D0%BC%D0%B0%D1%82%D0%B8%D0%BA%D0%B0#Russian
I think "we will have no more math" sounds rather poetic (or like part of a political speech where they repeat the line "we will have no more ___" several times) and would suggest using one of the accepted translations instead. However, I think it is a correct translation, and if you try it again you should report it.
It can only be "anymore" (one word) here. "Any more" (two words) refers to quantities (Would you like any more tea?). "Anymore" is an adverb that refers to time (I don’t like tea anymore.).
See https://www.grammarly.com/blog/anymore-vs-any-more/ for more. :)