Hi.
Exactly which sprite is not removed on collision sprite or enemy?
If you have small objects and high speeds, I recommend doing a step by step check. Here is an example editor.construct.net
If only the laser is not deleted and the enemy is deleted then maybe you have several laser sprites flying around and they overlapped each other, it is easy to check this by adding an action to stop time after the sprites are destroyed. After the event time will stop and you can in debug mode to see what sprites are left more accurately.