I went through several websites and found that the easiest way to peel tomato is to boil them . So, How long do we need to boil tomatoes so that you can easily peel them?
You don't want to boil them, you want to blanch them. This means you bring the water to a boil, cut a shallow cross into each tomato (scoring the peel), add the tomatoes (few enough compared to the amount of water that the water doesn't stop boiling) and let them boil for ~1 minute. Remove the tomatoes and dump them straight into ice water. Once cooled the peel should come right off.
Another method if you use a gas stove is to roast it over the cooking flame gently. To do this you can stick a knife into the tomato (preferrably in the stem part) and hold it over the flame while rotating it. Some of the peel will burn away and the rest will shrivel up which can be removed using bare hands quite easily.
This isn't a mass peeling method like boiling/blanching but I find it preserves the flavour better.