I NEED to know how to remove wall merge between an interior and exterior wall. PLEASE HELP ASAP!!
Assuming that you are trying to remove an ACA Wall Merge (and not just trying to prevent Wall cleanup), you have several choices:
1. If you want to remove all Wall Merges for a particular Wall, select it, and on the Wall contextual ribbon tab, on the Cleanup panel, select the panel title to expand the panel and choose the Remove All Wall Merge Conditions tool (WALLMERGEREMOVE command, if you like typing).
2. If the Wall in question is merged with multiple other Walls, and you want to only remove one (or remove one at a time to see the effects), select the Wall, and on the Wall contextual ribbon tab, on the Cleanup panel, select the Justification Display tool (if it is not already on). (The command is AecWallJustificationDisplayToggle.) Wall Merges will be visible by dashed arcs running from the center grip at the Wall's justification line to the midpoints of the justification lines of the Walls to which it is merged. There is a rectangular grip at the midpoint of each arc; select it to remove that Wall Merge.
It is propable user error, but I cannot get that to work. see pic attached
That is because that is not a Wall Merge condition, it is a Cleanup Edit in Place condition. If you want to remove that, select a Wall to get the Wall contextual ribbon tab to show, and then, on the Cleanup panel, select the bottom half of the Cleanup Edit in Place split tool and choose the Remove Single tool on the flyout (AecWallCleanupOverrideRemove command). Select a point near the intersection of the two Walls where the cleanup was edited, and the Wall Cleanup edits will be removed. (The Remove All tool, or AecWallCleanupOverrideRemoveAll command, will remove all in-place cleanup edits in the entire drawing, so use this only if that is what you want to do.)