Merging same row data in column into one

So i am having a trouble here. Below mentioned is the sample data

Here in LineItemCategory column Luxury Pret and Luxe Pret are same. So for visulaization i want to merge both of these and find the sum of LineItemQTY. Can any body help me with this.

When i visualize the existing data i get both of these as seperate categories as shown bwlow:

So again i just want both Luxury Pret and Luxe pret as same and sum of there LineItemQTY in visualization.

Thanks