Well noted with thanks.
My suggestion #1 is to delete "remove submission" button for assignment if possible. However, this button can be kept for the Submission settings with "Require students to click the submit button --> Yes". It is because with the default setting as "No" here, students can remove submission & Moodle allows NO files with "submitted for grading". If this setting is "Yes", student CANNOT remove submission without replacing file. However, with "NO", students can submit many times before the due or cut-off date. With "Yes", once students confirm the submission, they CANNOT submit anymore even the due or cut-off date is not finished yet.
#2 is that Remove button can be kept in this default Submission setting. However, just like the case of "Yes", student CANNOT remove submission files without anything.
#3 is that Remove button can be kept in this default Submission setting. However, if student removed submission, the submission status changed to "removed submission without anything" or simply "removed submission". This can make both teachers & students understand that the files had been removed by the students.
Thank you very much!