To salvage the top of the pepper, push the green stalk through the pepper top with your fingers and discard it, keeping the rest. [5] X Research source
Be careful when pulling open the pepper- the seeds inside are small and will scatter easily.
Alternatively, put a bell pepper horizontally on your cutting board and slice off the crown. Then turn it around and slice off the bottom. You should then be able to see through the pepper. Use a knife to remove the pith and seeds. Then slice the bell pepper into strips.
This method should allow you to discard the seeds without separating them from the core or making a mess.