QB Issue Resolution:

It will not affect historical transactions by making inventory items inactive but make sure the item has zero quantity before inactivating item. If the item has quantity, make adjust quantity first to zero and then make inactive.

To adjust Inventory Quantity to zero:

From the Gear icon > Lists > Product & Services > Select inventory item in question > Select drop-down arrow (next to Edit under Action column) and Select Adjust Quantity > Make New Quantity to zero and Save. You can also change an Inventory adjustment account field, the default is inventory shrinkage account.

adjust quantity.PNG

Resolution for Issue 'If I inactive a Stock Item which was used before in many Invoices and Purchases, will it affect past history. I mean after I inactivated it, if I print out a past invoice what will happen?' available: Yes (Solved).
Source: Intuit Community forum.

If I inactive a Stock Item which was used before in many Invoices and Purchases, will it affect past history. I mean after I inactivated it, if I print out a past invoice what will happen?: 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 Adjusting Inventory Quantities
Quickbooks Repair Pro will resolve it efficiently and affordably. Guaranteed resolution of your issue, or you pay nothing!

Error Recovery for Adjusting Inventory Quantities [Canada]
E-Tech is the #1 Quickbooks data migration and Conversion service provider.

Get 50% off Quickbooks Online

Click Here for 50% off!

Additional Support Options: