yes, easy using oxalic acid. Check the small hardware stores. It is a white powder you mix with water. Brush it on and let it sit, scrub a little, then rinse. Make it up using warm water is better then cold.
Using warm water and saturating it might be a bad idea. And I say might in all honesty.
All the teak veneer in my boat is delaminating. Why? I don't know but suspect moisture and the final blow, freeze thaw. But it is still delaminating 5 years after purchase and no more freeze cycles ....so hard to say.
I will just go back to the life she lived in for 22 years in heat and high humidity. Something ruined the glue in the teak laminates.
Maybe it was just a bad batch of Taiwanese teak...again..just info....
If just saltwater and a soft brush with lots of patience and little to no elbow grease does it then try TSP (trim sodium phosphate) available at your local hardware store. It's ok to clean the teak with it once a year. And then maintain with saltwater and a brush the rest of the year.