user25903: I setup a position in Arena. Then lets engine vs engine plays it after pressing 'Demo' button.
The problem is Arena put engine thinking as well into the moves list. (in green font). Check the screenshot.

How can I remove those marked in green font? I only want main moves (no variations or engine thinking).

user17823: Go to Options → Appearance → Movelist and under View uncheck "Show comments in the movelist". This should hide the engine thinking variations.
Alternatively, you can right-click in a move → Display → Comments.

25903: <p>I setup a position in Arena. Then lets engine vs engine plays it after pressing 'Demo' button.</p>
<p>The problem is Arena put engine thinking as well into the moves list. (in green font). Check the screenshot.</p>
<p><a href="https://i.stack.imgur.com/o8MCE.png" rel="noreferrer"><img src="https://i.stack.imgur.com/o8MCE.png" alt="enter image description here" /></a></p>
<p>How can I remove those marked in green font? I only want main moves (no variations or engine thinking).</p>
 17823: <p>Go to Options → Appearance → Movelist and under <strong>View</strong> uncheck &quot;Show comments in the movelist&quot;. This should hide the engine thinking variations.</p>
<p>Alternatively, you can right-click in a move → Display → Comments.</p>
