remove lxInternal attribute from a layout cell view

I have come across some layout views which contain no devices, and have no corresponding schematic.

However, cv~>lxInternal and cv~>lxInternal~>source are defined with db IDs, and items like cv~>lxInternal~>source~>lib return an empty string, eg "".

Using setq or the equivalent cv~>lxInternal = nil to try to remove the lxInternal attribute results in the values to instead be redefined as "FALSE", which just creates different problems.

eg

cv~>lxInternal = nil

then

cv~>lxInternal

will return the value "FALSE"

How do you remove the lxInternal attribute from a layout cell view that has no corresponding schematic view?