Regardless of the solution you’re using, always verify the plate properties and the loads on the merged surfaces!

Solution 1

1. Select the border(s) between the surfaces you want to merge.
   
2. Click on or hit DEL.
   • If the selected lines have a cross-section, the cross-section will be removed. Repeat step 2 again.
   • If the selected lines didn’t have a cross-section assigned, you’ll see a dialog box. Choose ‘Merge’. Result:
     

Solution 2

• Double click a border of the unwanted plate and set the length to zero.
• Repeat until the plate is gone.

Solution 3

Assume you want to remove the selected line so the two plates are joint.

• Divide the line in 3 parts.
  
• Use the translate function to move point A to point B and point C to point D.
  
• Result:
  

Solution 4

Work level by level:

• Select all plates, but NOT their borders. You can use CTRL, SHIFT or the menu Select.
• Hit CTRL+SHIFT+DEL. This will delete the plates but not the borders.
• Delete excess lines.
• Select all borders and generate a new plate.