$ rm /home/xx/.cache/clinica/data/atlas-Neuromorphometrics_dseg.nii.gz
When re-running the pipeline, Clinica should re-download the file.
For the working directory, what command did you run ? If you specified a working directory (with the -wd option), then simply re-run the command with the same working directory, Clinica will use the results cached in this folder. Feel free to inspect the working directory yourself, you should see some results if everything went well.
Hope this helps!
Best,
Nicolas