I do not want to continue using the old domain curtaincrust.pk, as I already have another domain, www.curtains.com.pk. Is there an option in Shopify to redirect from old domain to other domain.
@Princeweb Yes. Shopify allows you to redirect your old domain to a new one. You can set up a 301 redirect so anyone visiting curtaincrust.pk will automatically be sent to www.curtains.com.pk. This preserves traffic and helps with SEO.
You can do this by:
Going to Shopify Admin → Online Store → Domains
Click on your old domain
Choose “Redirect to primary domain” and select your new domain
Once done, all traffic from the old domain will safely go to the new one.
Are you planning to keep the old domain active, or completely retire it?
Hey @Princeweb!
Instead of redirecting the domain, the best is to link the new domain that you have purchase. It’s way more better then just redirecting it. Redirecting the domain is not best approach.
Here is the best way, I shared with you on how you can link a new domain instead of the old one.
Go to Shopify Admin >> Settings >> Domain >> Click on domain name and delete or unlink it.
After unlinking it now you need to link the new domain.
Here is the details shared on how to link the new domain with Shopify.
https://help.shopify.com/en/manual/domains/add-a-domain/connecting-domains/connecting-to-hostinger
Hope this helps.
If this was helpful, then mark as Solution and Like it.
Cheers 
Yes, I am permanently retiring the old domain, so I will attach the new domain and retire the old one. Will the method you guided me through work in this case or not.
Yes, I also think this is the better idea.
@Princeweb Yes, that method will work perfectly even if you are permanently retiring the old domain. Once you set your new domain as the primary and enable the redirect, all traffic from the old domain will automatically go to the new one, and you can safely stop using the old domain.
Very good Decision.
This is because, if you choose redirection then it will also take time to redirection which cause issue with the Speed Optimization. That say, you need to use the actual domain.
If you need any help to link the domain then feel free to reach me out.
I can not find here https://admin.shopify.com/store/f2d101-a7/settings/domains any option to unlink or del the current domain.
Well, you must add the DNS record in the hpanel of the Domain provider. Just delete that DNS records of the old domain. It will automatically unlink the domain.
I connected the domain but what type of protocol I should use with the domain name www or without www for example www.curtains.com.pk or https://curtains.com.pk