If you are seeking to reset your old iPad after transferring all your data to your new iPad, this is the simplest procedure:
What to do before you sell, give away or trade in your iPhone, iPad or iPod touch – Apple Support
This process will erase all data and personal information from your iPad - and remove the Activation Lock that will otherwise inhibit use by a new user.
Erasing all data from your old iPad, using this process, will not impact your new iPad or its data.
Note, however, that attempts to manually remove data/files from your old iPad may result in data being deleted from both old and new iPads - as the changes may be synchronised using iCloud.