You can delete multiple(range) lines if you know the line numbers:
:[start_line_no],[end_line_no]d
Note: d stands for delete
where,
start_line_no is the beginning line no you want to delete and
end_line_no is the ending line no you want to delete.
The lines between the start and end, including start and end will be deleted.
Eg:
:45,101d
The lines between 45 and 101 including 45 and 101 will be deleted.