Sale return is excess than outward supply.

Shiw the balance in Your next returns...

Can I claim itc in respect to that sales return in gstr 3b

As per my view No...

But, In case that is in Tax Invoice from customers then Yes....😇

My sales return belongs to 2018-2019 ,I shown separately in credit note in gstr 1 but this month I don't have sales to adjust that in 3b.so someone suggested that to increase the itc to that extent in 3b as there is no option to show negative

Only the option is add this credit note in purchase. and rectify the error while filing annual return for the FY 2019-20

No.... don't add it your ITC , the same is going to get autopopulated in your Annual return .

Many Tax payer is struggling through the same problem . Hence in my point view you should put the Mail to GSTN about this & reduce the same in month you got enough sale.
Yes I knew that it is to be done in September return but as due to limitations in 3B that it does not accept the negative figures you won't be able to reduce the same . So the mail to GSTN will help you as supporting documents in future litigation

Yes... I agreed to Mr Pankaj Rawat's view...