It is much easier to get paid charge-offs removed than unpaid charge-offs. There is no incentive for the creditor to fight the dispute, since they already have their money. So if you dispute the charge-off, the credit bureaus will send a verification request to the creditor. Most often the creditor will ignore the verification request. After 30 days with no response from the creditor, the credit bureaus will remove the charge-off form your credit bureau.
Unpaid charge offs can be much harder to dispute and remove. Always try to dispute the charge-off with credit bureaus first – often you can get the charge-off removed in the first round of dispute letters. However, it is possible for the creditor to ignore a verification request if the person still owed them money. Nevertheless, it is still worth a shot to dispute it and see what happens.