I booked a hotel using points. I now want to change the hotel (still a Marriott). Will I get the hotel points back from the first hotel booked? It is for this evening.
Your scenario, as many with Marriott lodging has several potential outcomes. You can influence the end result, but must work promptly, sincerely, and persistently.
Marriott imposed a one, two, and in some cases three day notification requirement for cancelling - your scenario lies outside of all those deadlines (since the soonest you could have booked the reservation was 11 months ago - and those policies were in place).
According to your profile you are Gold, so with a calm, prompt, and effective approach on your part, yes you can avoid the penalty (especially while concurrently booking another Marriott), but it is not a given.
Award stays also face the ugly scenario of, Yes, you do get your points back, but several properties have been known to credit back the points and charge the rate of that night (which is often ugly).
So get on the phone (soon, if not now), call and explain your situation and your odds are decent that they will let the Cancellation Policy slide - but don't take it for granted; and if by some chance you're turned down by a hardnosed rep, don't agree, just say, "ok, thank you" and call again - as shown many times, different reps have different viewpoints.
100% agree, and in your call that you are IMMEDIATELY making, ask if they can do all the transferring/booking for you on the phone - in fact, they may insist it as the only way you'd get it done without hassle. This is all assuming a points stay is still available day-of arrival.
Erc and mrwhipple13 are both on the money with their responses. The key is to remain calm when contacting Marriott. Even be apologetic if necessary (even though you have nothing to apologize for). Mention your Gold status, but don't hit them over the head with it - Marriott works hard to keep the Gold and Platinum level members especially happy. Erc is correct - don't get upset with an initial representative who decides that rules are never made to be broken. Either just thank them, hang up and call back and talk to another representative, or very politely ask if you could speak to a supervisor. Sometimes the initial representative believes that they don't have the authority to overrule the policy, but don't offer to let you speak to a supervisor who might/does. Also, please keep in mind a lot of representatives might not be as cooperative as normal in that they might be dealing with a lot of customers affected by Harvey. That's why your being nice, calm, and cooperative will really be appreciated.
In any event, I wish you all success.
With so many good answers, all I can say is
Retrieving data ...