Yes, you can omit all CommonLit Guided Reading Mode and Assessment Questions from a Library Lesson and choose to only assign the text to students.
Guided Reading Mode is automatically enabled for Library Lessons. To disable Guided Reading Mode, click the Guided Reading Mode toggle to set it to NO and click the "Assign Assessment Questions" toggle to set it to NO as well. Students will still be able to annotate, hear the text read aloud, and translate the text.
Students must click the "Submit Your Assignment" button at the end of their assignment in order to submit it and indicate to you that they have finished reading the assignment. Assignments without Assessment Questions are never marked as In Progress (only Not Started and Submitted), but you can view live annotations as students make them from the Student Annotations page. Click the highlighter button on an assignment on your Assignments page to go to the Annotations page for that assignment.
For more information on how to customize a Library Lesson, please see the FAQ: Can I customize which questions my students answer on Library Lessons?