There are multiple ways to reject candidates from the ATS pipeline.
Individually
You can open the candidate card from the pipeline
In the candidates pipeline overview section you will be able to either schedule an interview, place or reject them
From the Job Pipeline
You can hover on the three dots next to their name, to open additional actions
Click on reject
Bulk reject
Bulk-select the candidates
Click on more actions
Reject
Once the candidates have been rejected you will be able to choose to view them by selecting view all or view rejected candidates
Rejected candidates will have their cards visible with a red tint