Like the other guy said, there’s no immediate need to delete the account. And someone else wont be able to pick the address up after you, if you do.
I’ll probably leave google eventually, as well, but I don’t intend to delete my account. The process of using google services less and less has been ongoing for years for me, and I will just use them less and less, until I no longer do at all.
Where email is concerned, I’ll just have whatever my new email is pull in my mail from gmail for a while, and as I receive email concerning various accounts to my gmail, that’s when I’ll go in and change them over to use my new address so the old inbox gets less and less mail.
Then, eventually, when I haven’t touched it for years, I might take the final step of actually deleting it. But probably not.
This is a very, very bad idea.
SSDs are permanent flash storage, yes, but that doesn’t mean you can leave them unpowered for extended periods of time.
Without a refresh, electrons can and do leak out of the charge traps that store the ones and zeroes. Depending on the exact NAND used, the data could start going corrupt within a year or so.
HDDs suffer the same problem, though less so. They can go several years, possibly a decade, but you’d still be risking the data on the drive but letting it sit unpowered for an extended time.
For the “cold storage” approach you should really be using something that’s designed to retain data in such conditions, like optical media, or tape drives.