IIRC from looking at this feature somewhat recently, they explain that they are not necessarily deleting the data, only not associating it with your account. O

IIRC from looking at this feature somewhat recently, they explain that they are not necessarily deleting the data, only not associating it with your account. OTOH, from what other commenters are saying it sounds like they may want to delete (some of) the data but currently do not do so because it is shown in the account. Presumably they will still keep whatever they find useful. I hadn't used my account in a while and was going to just "delete" what I could and keep the account. They have a "download your data" button but refused to let me use it claiming they couldn't be sure it was really my account (but not providing any way to convince them), so at that point I decided to delete. Hopefully they did actually delete it. For me, it still showed the older history after I enabled the "delete" older history option (possibly it would have been removed after some delay), so I manually deleted it (it wasn't all that much) and that did seem to remove it.