Can I change my non-B visa to a marriage visa in Thailand?

Are you actually on the 90-day non-B visa, or are you on a 1-year work extension?

If you're on a visa, you cannot do anything except leave without a re-entry permit to cancel your entry stamp and then apply for a new non-O visa either from a Thai embassy outside of Thailand or from your immigration office after you return as a tourist, if your office allows conversions to non-O inside Thailand. This is because the first extension must be for the same reason your visa was issued for, so you cannot apply for a marriage visa or marriage extension from a work visa, you can only apply from a work extension to a marriage extension.