How Delete, imported chk boxes??

[B. abe]

A while back, I haphazardly imported some values that included CHECK BOXES.
Since then, everything tried; has failed to delete them.

Because they are now contributing to Chart,(series), malfunction; I need to
delete them, BT HOW?

[ON REQUEST, THE AFFECTED FILE CAN BE eM]

Thanks for the help.

Barbera (e-mail address removed)