They are both correct, depending on the context. The simple present or the present simple are used to refer to the specific tense. Example: Use the simple present (tense) for routines, habits, and facts. Simple present or present simple are used in headings and short descriptions. Example: Simple present: I get up at 6:00 a.m.

Thank you Chris.

Usually, “the present simple” is used as a short form of “the present simple tense.” “Present simple” is used in chapter headings and section headings and index entries.