I ripped the old carpet from the kitchen, exposing the plywood
underneath. I want to to install vinyl tiles. The old carpet came off
without any difficulty. There was no foam or padding of any kind
underneath. However, there is still old glue on the plywood. It must
have been applied using one of those grooved spreaders because I can
clearly see the groove lines in the glue. The glue does not appear to
be more than a 1mm thick. However, I am concerned if I can stick the
vinyl tiles directly over it.

Removing the glue would be quite a lengthy project. Sanding did not
work. I tried a carpet glue solvent. It worked (with a lot of hard
scraping), but I am concerned about the side effects. It is highly
flammable and a health hazard, and the whole house smelled for two
days even though I only tested it over a 5 sq.ft.

Question: is it ok to glue the vinyl over the old glue? I am not an
expert in these things, but I imagine that the new glue will flow
within the old grooves and form a flat surface for the tiles to to
bond to.

Thanks!!