I migrated to 1password account, removed all standalone vaults. I have 5 personal devices using 1password. Is it possible to remove dropbox since it is now limited to 3 devices only.
Welcome to the forum, @fishjacob! Please don't post the same thing in multiple threads, that slows the support experience for everyone including you. I've combined your questions into this one separate thread, hope that's OK.
The answer to your question is yes: if you have a 1password.com account that contains all of your data, then you don't need to keep standalone vaults and Dropbox sync. What you should do is make certain that none of your 1Password applications still have a Primary vault (which is the standalone, Dropbox-synced vault), or any other secondary standalone vaults: you should have only the vault(s) that are part of your 1password.com account, containing all your data.
If you're looking to remove the Dropbox app and service from your devices, I'd direct you to Dropbox's documentation for assistance with that. But if you're just looking to get rid of Dropbox sync in 1Password, that's fine -- presuming all of your data is already in your 1password.com account's vault(s). Let us know if you have questions.