Summarize this article in one sentence.
Close off all other routes and leave a single exit to your house open, like a wide open window. If getting to a window in the same room the squirrel is in puts you too close to the squirrel for your own comfort, you might: Open the window in the room next to the one the squirrel is in, leave the door open to that room, and close off all other routes. Drawers, cupboards, and other nooks and crannies comfort the squirrel, as these may remind it of its natural habitat or its nest in the knothole of a tree. By closing these off you can prevent the intruding squirrel from hiding out in a safe place as opposed to hightailing it out of your home. Especially in inhospitable weather, like in winter or during a drought, a squirrel may be especially hard to remove if it has a food source available. Squirrels, like other rodents, have sharp teeth that can gnaw through even thick bags. Remove even closed food sources. Squirrels, much like many animals, are sensitive to certain scents and other kinds of stimulus. In particular, squirrels have a dislike for the smell of cider vinegar, so you might want to soak some rags in the stuff and put them in the room in which your squirrel resides.  You might also leave a radio playing constantly in the room the squirrel is in to drive it out. A bright light left on throughout the day and night can also make your house less appealing to squirrels. Predator urine can be bought from farm supply stores, sporting good centers, and online retailers. Soaking rags in predator urine, like that of a fox, could lead to your squirrel invader beating a hasty retreat. Squirrels in your attic or other narrow spaces, like a wall or crawlspace, can be difficult to get at without coming into too close of contact. In this case, you should bang on the rafters and walls.  Even entering your attic and speaking in a loud voice may be enough to chase your squirrels out of your home. These loud noises will often provoke a squirrel’s flight response, making it flee through the escape path you’ve provided. There are many different kinds of humane traps available. These are specially designed to help remove squirrels from your home. You can buy a humane trap at most hardware stores or from a general online retailer.  A one-way door is a kind of trap that lures squirrels in but does not let them out. When using this kind of trap, you should take the squirrel at least 3 miles (4.8 km) away before releasing it. Depending on the kind of trap you buy, setup and squirrel removal may have different procedures. Always be sure to follow the directions that come with your trap for best results. If the room does not have a door, close all other doors that lead to that room and put up a makeshift barrier if possible. You’ll want something the squirrel won’t able get around or hop over, like a door sized piece of particle board or plywood.  If you do not have particle board, plywood, or another door barrier available, you could always remove a door from another room and use it to block off the room the squirrel is in. When using a door from another room, you should anchor the door into place by putting something heavy, like a stack of books, boxes, a bag of salt, or a bag concrete at its base.

Summary:
Provide an avenue of escape. Close off hiding spots while keeping your distance. Remove all food sources. Create some incentive to leave. Create loud noises for squirrels in difficult spaces. Use a humane trap. Leave the room and seal it off if necessary.