How to remove (delete) a node?
Look a picture.

I presume you're modeling in CAESAR II? If so then:

Assume you have this:

10-----------20--------------30
elmt 1 = 10' elmt 2 = 10'

To remove node 20:

1) Change node 20 to 30
2) Change the length of elmt 1 to 20'
3) Delete element 20-30

Another way:
using Rich's example with an element order 10-20, 20-30
with the current element as 20-30; use Insert After and specify From and To node as 10-30; click on Close Loop; add whatever check boxes you need for this new element (e.g., bend); then delete 10-20 & 20-30

The bend in a node 30 is, but isn't displayed in 3D view now.

I'm just guessing here:
CAESAR II requires that the two elements that form the bend must be defined one after the other. For example, if I have a bend at 30, I must have 20-30 followed next with 30-40. (I can't go 20-30,40-50,...,30-40.)

You're right. Really the problem was in it.

Interesting topic. It would be nice to be possible merge elements into one element.