I have had some cases where it is possible but it depends on how long the stain was there, if the moisture problem has been abated, etc. You can usually tell by the severity of the stain. If it’s dark, brown or red, chances are it won’t come out. If it a light yellow color it may be possible. Of course finding out the where the moisture is coming from is the most important. Even if you are able to remove the stain it can come back