Since you asked about a quiz, @KOverall , I assume you mean the Essay Question type and that students are attaching the file via the Documents button in the Rich Content Editor toolbar:
Unfortunately there is not an option to disable the RCE toolbar in Classic Quizzes.
However, New Quizzes does have this option! The RCE is on by default but instructors can decide not to allow it. There are other options for essay questions that New Quizzes has:
More information about these options is available in the Canvas Guides document
