I'll cover some information here of which you are probably well aware and I'm going from memory, but please bear with me. There may be some differences based on the versionof JDE. Which version of JDE are you using?
When building a menu, you create a folder (a type of task, if I remember correctly), and a task that you want to access via the folder. In addition you create a list of tasks that are accessed via the folder (a relationship, I think there is a relationship object created for each task in the list). So there are at least 3+ objects involved. All will be automatically put in your default OMW project. To promote these objects, you create another OMW project and move all the objects into it. It is possible that pre-existing tasks could be included in the relationship objects, in which case the task objects will not be created in your default OMW project.
Now, for argument's sake, I'm going to assume that you created the 5 tasks and that only these 5 tasks are in the folder. Thus you will have 11 objects created in your default OMW project. You create a new OMW project and move all 11 objects to the new project. You then promote the project from 21 to 26, copying the 11 objects from DV to PY.
You then receive instruction that 3 of the tasks are not needed and should be deleted. To delete the tasks and relationships you "demote" your project from 26 to 21 (this may not be direct from 26 to 21, you may have to "demote' via another project status maybe 25; or you may have to create the this functionality in OMW rules). I'd prefer to delete the relationship objects first, then the task objects. Now you delete the 3 relationship objects from within the OMW project, using the delete button, which will show a window of options. One of these options will be delete on promotion. Select this option and promote the project. Move the project back to 21 and repeat the process for the 3 tasks.
From your descriptions, I'm assuming that the above process to delete was not followed.
When you look at your menus, in DV you see 3 child tasks. In PY you see 5 child tasks.
When you look at the OMW project when logged into PY, you see all 11 objects and they all exist. Please confirm you see this in PY.
When you look at the OMW project when logged into DV, you see all 11 objects and but 3 relationship and 3 task objects do not exist. Please confirm you see this in DV.