security Upload Clear mapped Items in Source

It would be great if security could be reset per user / list combination when importing new security.

At the moment you need to specify:

1) Exactly what you have in read or write and load it NONE

2) use a top level which you then load on NONE

in order to clear the security before applying new security.

It would really help the security management if you could tick a box in a security process which would say clear security before load on all users/lists that are mapped in the upload. Then we do not need to create special processes in order to clear the security via the NONE column and it would safe a lot of time.