Is it safe to remove hidden "Generic Volume" storage volumes from the device manager?
Its never safe to remove any volumes, ever. Unless you know you want to remove them.
The question is why do you want to do it? What problems are you experiencing?
Generic Storage volumes are like USB drives, virtual drives (poweriso), virtual drives for virtual machines.. etc.
Unless its causing you problems there is no need to remove it.
PS- Some notebooks also use Generic Storage Drives for SD/MMC slots.. and usually when you insert a card it will re-jig the driver to the appropriate driver eg. SD or MMC.. cant be both at the same time.
-EDIT (The OP commented that he is experienced intermittent freezing in windows - that's why he was browsing the device manger to find the culprit)
Random freezing could be caused by a failing Hard Drive, as its hits bad block, the whole computer stops for a second or more.
If still doing it.. most likely Motherboard/GFX/RAM (Hardware related)-- then you need more intense testing, most likely by an experienced Technical person..
Hope this can help solve the issue.
Actually, it is.
I've done it several times before with no adverse effects whatsoever. The only "catch" is that if you plug in the devices later, Windows will have to reinstall the driver. But that's nothing troublesome at all.