Here's a reminder of the issues you may experience if you're performing deletes from your heap table:
https://www.red-gate.com/simple-talk/sql/t-sql-programming/delete-operation-sql-server-heaps/
For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden