How can I reset the values of the Nulls I used as controllers to zero?
I already built the spine and head. Do i have to undo everything?

Thanks

there is a dropdown on all Objects called ‘Modify Pre-Transform’
in there are a bunch of options, one of which is ‘Clean Transform’
this will take the values in Translate, Rotate and Scale and shove them into the pre-transform of the node.
see : http://www.sidefx.com/docs/houdini/basics/objects.html [www.sidefx.com]

Thanks goldfarb but I already have scripts on them and I cannot clean them without rebuilding everything

can you post an example hip file with a simple example - just a null with the expressions