You should have no trouble leaving the US if these warrants are for a failure to appear. However, entering a foreign country may be problematic. In the era of advanced security measures, this warrant may well turn up. Additionally, some countries require a visa for entry. Typically at that point a warrant would show up in a background check. Further, upon re-entry into the US you may be detained and taken into custody. Bottom line, don't leave the US until you have taken care of these warrants.