Exporting Citation Records:

LexisNexis Academic provides minimal metadata, making it difficult for Zotero to detect sources.

• You can select the "Export Bibliographic References" icon in the upper-right and then select the Export Type as "Download Bibliographic Data for other generators, e.g. EndNote."
• This will give you an RIS file to download and import into Zotero. However, please check the record after importing, as some fields might be empty.

For more information visit this link:

Backing Up/Storing Zotero data:

To back up your Zotero library, locate your Zotero library, close Firefox or Zotero Standalone, and copy your 'zotero' data directory to a backup location, preferably on another storage device. As with all important data, it is a good idea to back up your Zotero data frequently.

See instructions posted on zotero.org: 

Deleting your Zotero Account:

You can delete your account by logging into Zotero and navigating to Settings > Account Settings.  At the bottom of your account settings page you will find a link to Permanently Delete Account.