The simple answer is yes. You may run into time difficulties if the buying wants transfer to another registrar, but if they are willing to keep the domain at the existing registrar,then you can simply push it into their account at the same registrar.
If it's recently been renewed, you can still transfer to another registrar. There is a gotcha! There is an ICANN rules which says (paraphrasing) the new registrar is not obligated to add another year of registration in it's been renewed in the last 45 days, even when the person pays the transfer fee. In these cases the buyer should check with their preferred registrar, what their policies are. Some implement this rule, some don't. The transfer will still proceed however.
If it's recently been transferred, there is another gotcha! ICANN has another rule which states a domain cannot be transferred for 60 days after transfer. All Registrars implement this rule. If the buyer is prepared to wait the 60 days, you could still sell the domain and change the nameservers to the buyers nameservers. They then implement a transfer after the 60 days.
If the domain is registered at GoDaddy or any of it's resellers (WildWestDomains/BlueRazor), they will lock the domain for 60 days for ANY change to the REGISTRANT INFO. You can still push to another account but you will be unable to transfer out to another registrar for 60 days.