Deleting old, networked, mapped drives

In Explorer, there are sometimes two network drives W: that appear,
which I presume refer back to eight years ago when my handed-down PC
was part of a company LAN. I use my PC standalone exclusively. How
do I remove the W: drive entries from Explorer? I've searched the
Registry for references to W: without success. Is there a specific
key I should be looking for, or somewhere else I should be looking to
delete references to nonexistent drive W:? Thanks.