I had an blow-up of BGA in my outdoor emersed tank. Since it's a tear-down / re-scape. I would suggest a few methods that worked for me.
In all cases phyicicaly wipe/remove as much as you can. depending on the plant you can swish in a bucket of tank water or up in a jar and shake. Heavy nodyy plant like crypts could be rinsed under cool tap water too.
Method #1 - H2O2 in a spray bottle. Soak the plant 1-2min dwell time more delicate = less time. Them dip in clean cool water.
Method #2 - Small plants Water lettuce babies, DHG, HC etc. Put the H2O2 in a quart jar enough to cover the plants, shake, rinse, place plants in cool water.
The spray bottle works well on driftwood, rocks, glass etc. too.
i also spot treat with a bovine shringe I got at a Farm Supply store. But, it's less effective that a spray or dip. However, safer if you watch your dosing.
H2O2 dip % ?