Hi, I need to replace a section of sill plate (approx. 10 feet) for the main load bearing wall in my house. The wood has been damaged by termites (called Terminix already). My question is how much can I remove at a time so I don't have to build a temp wall? I will be doing this by myself and I am a bit nervous. A contractor a Home Depot said I could remove up to 6 feet at a time and would be fine, but I am not comfortable with that. Any help is greatly appreciated.

We do this work all the time. Its not that hard.
However to tell you that you can remove up to six feet is scary. Although six feet may be possible, you do nor they know the load profile on the floor joists above. Do not take any chances and support the floor properly below. Chances are nothing will move, but there are cases when it may and once that happens you have some difficult repairs to do if it does.

You need to purchase or rent a few steel pole jacks to support the floor joists above.
Simply place a 2x8 or 10 on the floor of the basement. Then take a doubled 2x6 and tack nail it on the bottom of the floor joists about 18 inches or so (enough so you can get to the sill to work).
Set the jacks (four) evenly spaced and put some pressure on the joists so they just begin to slightly move or creak.
Cut out the sill joists and dig out the damaged wood as needed. A recip saw works best here.
Be sure to remember that there are some steel rods that would be holding the old sills in place that will end up being cut off. If at all possible do not destroy these and loosen the nuts so when you put the new boards back in you can knotch them and refasten the sills back in place.
You must remove all of the joists where damaged. This may include the outside rim joist as well. This will require that the outside siding be removed along the bottom to access this area.
Once all the damaged wood is out (easy part) then hammer in the new wood and toe nail all joists and complete the job.
Remove the jacks and temp supports and your done.

My suggestion is to have this professionally done. Its not that costly although most folks think its so. Be sure to contract with someone who does this type of structural repair as a living. Altough most carpenters can do this, those that do this as a living can get it done in less then a day and it will cost less as they have all the stuff on hand to do the job. While most carpenters would take longer and would not be prepared for those hidden surprises that oftentimes comes up duing the process.

Thank you so much for your advice. I am thinking that I might have it professionally done as it sounds a bit scary. I think I like the idea of doing it myself more that actually doing it. Thank you again. I sure appreciate all of you who are so willing help.