1. Copy the file checkout_index_index.xml from vendor/magento/magento_checkout/view/frontend/layout directory into this location depending on your theme's name and vendor: app/design/frontend/{vendor_name}/{theme_name}/Magento_Checkout/layout/checkout_index_index.xml.
2. Delete or comment out the following code from the checkout_index_index.xml file that you copied over.
<item name="progressBar" xsi:type="array">
<item name="sortOrder" xsi:type="string">0</item>
<item name="component" xsi:type="string">Magento_Checkout/js/view/progress-bar</item>
<item name="displayArea" xsi:type="string">progressBar</item>
<item name="config" xsi:type="array">
<item name="deps" xsi:type="array">
<item name="0" xsi:type="string">checkout.steps.shipping-step.shippingAddress</item>
<item name="1" xsi:type="string">checkout.steps.billing-step.payment</item>
</item>
</item>
</item>
3. Flush the cache.