In principle, following two conditions are required to delete your sequence data;

  1. The sequence data has not yet been publicized
  2. The accession number of the data has not yet been published.

Please send your request from contact form with the following contents in clear English.

  • Accession numbers:
  • Reason in brief:

Just for information, we can restrict access to your sequence data that have been open to the public, if the conditions are right.
See also the following item.

References
How to restore the released data to private?
Why is the retracted data still available?
INSDC Status Document