I have a 1099-misc form for an IBM non-qualified pension for my deceased husband. Why has Turbo Tax entered the income on a Schedule C?

[Carl]

Because the pension plan administrator issued you the incorrect form. They should have issued you a 1099-R, not a 1099-MISC. First, you need to delete the 1099-MISC as entered, and if necessary delete the SCH C. Only after you've done this, should you enter the 1099-MISC per the guidance in the answer box below.
To delete the SCH C, under the Personal Income tab scroll down to Business Items and elect to start/update Business Income & Expenses (SCH C). If you see anything listed there with a Delete button next to it, click that Delete button, then YES to confirm the deletion. That takes care of getting rid of the SCH C.

[Carl]

Reporting 1099-MISC (box 3) that is not self-employment income

Under the Wages & Income tab (or Personal Income tab) scroll down to Other Common Income and elect to start/update Income from form 1099-MISC. Then click YES to indicate you have a 1099-MISC.

Enter the 1099-MISC exactly as printed, and then Continue.

Enter the reason you got this money – be it scholarship, bonus, streaking butt naked across the 50 yard line of the super bowl, whatever. Then continue.

Select None of these apply, then Continue.

Select No, it didn’t involve work….. and Continue.

Select ONLY the tax year for which this specific 1099-MISC was issued. Do not select the year that you received the 1099. Select the year for which the 1099-MISC was issued. Select no other year. Then Continue.

Select No, it didn’t involve an intent to earn money, then Continue.

Select NO, then Continue.

Click the DONE button, and that does it.

[knitroom]

My husband received a 1099-MISC for this income every year since he retired in 1997.  He died in 2017 and I still receive the payment and 1099-MISC.  This is in addition to a regular pension and 1099-R.  And I have no idea what it is for and neither did my husband.

[knitroom]

I tried the fixes you suggest and TT still wants me to fill out a Schedule C with a type of business code, business address, etc.

[Carl]

That's because your first attempt at entering the 1099-MISC created the SCH C. Deleting or correcting your initial attempt does not delete the SCH C. Do this:
Under the Personal Income tab scroll down the Business Items and elect to Start/Update Business Income & Expeneses (SCH C). If there is "ANYTHING" shown there with a delete button next to it, click that Delete button, YES to confirm the deletion, and continue working through until returned to the list of items under the Personal Info tab.
That "should" (and most likely will) get rid of the SCH C permanently.
Then check the 1099-MISC that you entered using my guidance above and make sure it's still there. If it's not still there, then just re-enter it using my guidance above, and that "should" take care of things.