Hi, @Vincent Muchiri
For the first PC, you can have a try of this method, Go to https://portal.office.com/Account/#home and sign in using your work or school account, if prompted. From the Install status tile, select Install options. Then under My installs, select the down arrow next to INSTALLS to reveal the installs for Office or other products. Select Deactivate to deactivate the installs you no longer use.
For the Other PC, we recommend you to re-install Office 2019 and activate it use the same method. If you meet with any issue about activation, try contact contactus
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