1. I may be wrong, but from what I understood from your query, I have 2 answers.
   
   If you want a filter to filter the asset by end customer or contract type, you need to have those in a custom asset field. Once you have all the assets filled with this info, you can go to add a filter in the assets, and you will see the custom field option to set as a filter.

1. If your query is to remove all these standard filter options that appear op top when looking at the assets, you can simply delete them by clicking on the  filter and the delete button.

2. 

I hope it helps :)