We have field which needs to be removed from the visual flows without changing anything else. That field's datatype has to be changed which isnt possible unless we remove its references in the inactive flows. Any idea how to delete it?.
Unfortunately you are not able to do this with a Visual Flow that has been activated, you would have to Save As either a new version or new flow and delete the flows that access the field.
Then in the new Flow or version remove the reference to the field, delete the old versions and then change the field data type. Then go back into the new working version and add the reference to the field again and it will have the correct datatype.
The only other way round would be to create a new custom field with the correct datatype, but again that will require a new version of the flows to be created which references the new field.