Hi,

If you are looking to clean up the database from the transactional data that you have created in the db for testing purpose, you can use this app, which will clear all transaction data keeping the master data as it is: https://apps.odoo.com/apps/modules/15.0/om_data_remove/

Thanks

Hi.
1. Ensure you have the necessary access rights.Make sure that your user account has the appropriate access rights to delete records.                
2. Create a default pricelist:                
3.Go to the sales and under configuration select pricelists.Create a new pricelist with default settings and make sure it is selected as a default pricelist.               
4.And assign the pricelist to the quotations.

Hope it helps