how to reduce the height for one character?

FontCreator - Font Editor FontCreator - Support
1

is it possible to reduce the height of winAscent and winDescent for one character not for the entire font??

2

No. The value of Y Maximum determines the position of WinAscent that your font needs to avoid clipping, and the value of Y Minimum (in Font Information) determines the position of WinDescent to avoid clipping.

If any contours exceed these limits, use Font Properties, Metrics, Maximum Calculate to fix it. This will increase the default line-spacing for Single line-spacing in Applications.

Double-clicking on these values in the Font Information dialogue will locate the characters in the Overview or Glyph Edit Window (best), where you can fix the issue.
Font Information.png

3

Thank you Bhikkhu Pesala.