They aren't doing it b/c they know you will do it.
I as doing more chores than my mom by the time I was 10. Every day I cleaned AND picked up, and every Saturday I did deep cleaning, as in mop/dust/windows/vaccuum... and then I did it during the week as well when needed and as I got older, I also made dinner, was a cheerleader, in theater and I worked 20 hours a week after school.
So, no tv, no computer, no texting, no going out with friends, no soccer practice... until they get their butts in gear and do their responsibilities. My mom had lists and chore charts. We couldn't do anything until everything on that list was crossed off by a specific timeframe.
And yes, I would get rid of skateboards and bikes if they are leaving them in the front yard. For one, it is unsighlty. For two, it is a hazard. For three, it is just asking someone to come and steal it. I would probably not allow the kids to have them for a full week. Then they can earn them back. If it continues to be a problem, I would sell the items on craigslist or drop them off at goodwill.