To have glucose model molecules easily fit together, you need to remove the hydroxyl groups (OH).

Here's why:

* Glucose is a sugar with a ring structure. The ring structure has multiple hydroxyl groups attached to it.

* Hydroxyl groups are polar and create hydrogen bonds. These bonds are strong enough to hold the glucose molecules together in a rigid, crystalline structure.

* For easy fitting, you need flexibility. By removing the hydroxyl groups, you eliminate the hydrogen bonding and allow the glucose models to rotate and move freely.

This is a simplified explanation for modeling purposes. In reality, glucose molecules interact through a complex network of hydrogen bonds that are crucial for their function in biological systems.