[RWP] Deleting items

[Roland]

Hello,
this might be a stupid beginner's question, sorry for that.
I have 5 tracks with one MIDI item on each of the tracks.
Now I want to re-record the item on - let's say - track 1.
If I had just recorded it I would simply hit ctrl-z to undo the
recording - this works just as expected.
Now I want to get the same effect by deleting the item.
* I move to track 1 with up-arrow.
* I hit ctrl+shift-right to get to the first item and select it.
ReaAccess sais: "1 loop item 01 ReaSynth recorded Midi - selected 1 item"
* I hit del to delete this item.

Effect:
The item gets removed but unfortunately items on other tracks get
deleted too unless they are longer than the one I just deleted. In other
words Reaper seams to cut out all of the song which was timewise covered
by the item.
So my question: How do I simply remove the item leaving everything else
in place?
TIA, Roland