Suicide is a very serious issue which is why we do not allow posts about it. Instead, when we remove those posts, we reach out to the member to provide support with links to the suicide hotline and website where they can go to get professional help. That same information is also available in our FAQ here. http://www.girlsaskguys.com/faq/account#122
I am not an admin but I would delete them because I don't want to encourage suicidal behaviors and I would not want the responsibility of dealing with suicidal people. That is not what this site is about. When those questions are deleted, the poster receives an email explaining the deletion and encouraging them to seek professional help for their problems. That is the only rational response a site admin could have.
If someone is suicidal then it's best for them to get help from someone actually certified to help, not a website full of strangers who can potentially make things worse. If the question gets removed for suicidal reasons then the asker is given a message with information and phone numbers they can call for help so it's not like they're just ignored.
It's because they don't want other members here to actually encourage suicide or tell someone they should do it. It is likely a liability issue for the site. What happens is this: when a member posts such a question, it will get hidden/deleted, and the site admins will reach out to that person via PM to offer resources and support websites or phone numbers they can call for help.
That is because they believe it will bring pessimism, and might create a bad influence on this site. Plus suicide is a negative thinking and might spread negativity, defeatist attitude on this site and that's what admins don't want.
Because admins are scared little kitty!.. Because they don't want us to help people who are really about to die. Because they care about making this website a Happy playground!.. So more people join in here.. Means more traffic and more money. Because admins cannot stand attention whores on their website.. Because admins don't really care if you die..