QB Issue Resolution:

You should be able to click the X and it goes away

if that does not work, right click on the item and select make active

if that does not work, click on the item to highlight it, then use the button bottom left on the item list and make active

Resolution for Issue 'I can NOT reactive an item that i put an X on before. How do i take the X off and reuse that item number' available: Yes (Solved).
Source: Intuit Community forum.

I can NOT reactive an item that i put an X on before. How do i take the X off and reuse that item number: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for button bottom
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Error Recovery for button bottom [Canada]
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