Closing a street
If you've knowledge of planned roadworks or you come across a a closed street, the best thing to do is request a closure. As a starting editor you're not yet able to set closures yourself. Requesting a closure can be done via the Slack closure channel. A closure is instantly active and is used for temporary blockades.
Another way to prevent routing going through a street is by adding a restriction. Restrictions are used for blocking a street on specific days, times or blocking specific vehicle types. Restrictions are not meant for temporary situations, like roadworks or accidents. They are really part of the map. Restriction changes need a map update, so they will take probably one or two days to become active.