It's important to keep track of lost reasons. We've set default reasons but everyone's business is different so you're bound to have custom ones.
Good thing you can add/delete and edit lost reasons in Salesflare.
Just go to Settings > Customize fields.
Click on the Opportunities tab at the top.
If you have multiple pipelines, you can select which pipeline you want to edit a lost reason for in the top right corner.
Scroll down to Lost reason* and press the pencil sign to edit.
Here is where you can add, delete or edit your reasons. Just press Save and you're done.