Ignoring a project means it will be hidden and you will not receive any notifications regarding the project updates.
You can use the filtering options to change the visibility and see hidden projects again.
(please see the link at the end for further information about filters).
1. Click on the project you wish to ignore
2. Click the drop-down menu where it says Watch, and select Ignore.
3. The project will now be hidden unless filters are changed. To learn how you change your filters please click here.