My experience in teaching adults to ride a bike indicates it is not so simple as some would portray.

Yes, remove pedals and have them scoot. Firstly on flat ground as bunny hops, then kangaroo hops. Then put the pedals back on, etc, etc.

But there are a number of other factors that come into ADULT training as opposed to kid training.

The first is the considerable fear factor. It cannot be underestimated. Invariably, the process of learning to ride a bike is very stressful. The indicators are shaking fingers when a hand is held out horizontally, sore hands from gripping the bars very tightly, sweating for reasonably low effort, and so on.

Routine also is important. People who "know" how to ride a bike do it almost intuitively, and unfortunately, there are many many bad habits that interfere with getting adults to ride properly. In my experience, there are too many to list, but... it can result in unwarranted injury (even broken ankles and stuff like that).

Our courses also test out people's ability to balance. And we demonstrate how it is essential for them to look ahead when starting to pedal, and to "look where you want to go". It's an adult learning thing whereby understanding why things work the way they do assists in them being able to do those things.

Learning sessions should be kept short. Each of the two sessions in our course cover two hours, with about half classroom and half practical. Many breaks are taken in the practical because of the emotional and physical stress. We usually have people riding before the end of the first two-hour session. The revelation expressed by the riders themselves is worth the patience and effort for everyone concerned.

If the OP is serious about helping an adult to learn, PM me and I will send you our material to assist you in understanding the issues, and how we go about the process.

Essentially, teaching adults is vastly different from teaching kids. And a tutor should NOT be emotionally attached to the student.