You can try the below mentioned steps as that might help you:
1. Go to the Develop module and make your Global Adjustment. When you are happy with the exposure, tones, contract, clarity, etc. go to step 3.
2. Select the local Adjustment Brush in the Develop module and select a size that is big enough to paint over the background. Add a small feather enable Auto Mask so that Lightroom will do most of the selection work for us. Set Density to 100.
3. Paint over the background with the brush. Make sure the cross hair is on the background so that Auto Mask option doesn’t paint over your subject. You can press the ‘O’ key to show the painting overlay (default is red).
The overlay will make it easier for you to see where you are painting. If you make an error paint with the Alt key (Windows) / Option key (Mac) to erase.
For more information please check this video: Produce a white background in Lightroom - YouTube
Please let us know if it helps.
Auto Mask can sometimes leave a visible line or uneven mask edge, but your brush work looks good to me.
Looks good to me as well.
Thanks guys , you help me big time .
your knowledge is priceless .