Great question @davis ! For normal demo accounts with brokers, you cannot withdraw money because it is simulated. For prop firms they compensate you with a "payout" after you meet some trading milestone to be determined by them.
However, the payout from a prop firm is not the consequence of the trades you placed on your demo account, they only pay you that money as a means of encouraging others to use the prop firm.
Think abut this: 100 people buy a prop firm challenge and only 5 people receive a payout so clearly they use the money from the 95 people to pay the 5 people.
Although the prop firms themselves will argue that when you place a trade on a demo account, they "mirror" the trade and execue it on their own live account hence the profits which they give to you as a payout, but there is not much evidence to backup their claim.
So, if you qualify for receiving a payout from a prop fir, you can withdraw it by logging into your client area and clicking on "withdraw" or "request payout". The funds will usually be credited into your account number after some days.
