Step 1:

• Create csv file with only 'sku' and 'retail_price'.

Only create header with 'sku' and 'retail_price', do not add any other field in header with empty value, else existing data will be replace with empty value.

Step 2:

• Go to Products > Search Products

Step 3:

• Click on 'Import' > 'Product'

Step 4:

• Select 'Ricemill (CSV)' format
• click on 'Overwrite existing item data'
• upload the csv file create in step 1 and click 'Upload'