How to merge partition in macos catalina
I agree with Gilby's answer with respect to having the Projects volume stored in the same container as the Macintosh HD volume. This answer involves merging while attempting to preserve the Projects volume in a separate partition.  Here, I assume there is no data to be saved on the Untitled volume. You can not directly merge the partition containing the Untitled volume into the partition containing the Macintosh HD volume, because the partition containing the Projects volume is between these two partitions. This answer will clone the Projects volume to the partition containing the Untitled volume, then merge the partition that contained the original Projects volume into the partition containing the Macintosh HD volume

The example used in this answer was taken from a virtual machine with Catalina installed on a much smaller internal drive. The drive was not encrypted.

The steps to clone and merge are given next.

Click on the Disk Utility window and then press the ⌘+1 key combination to insure the proper sidebar is displayed, as shown below.


First, highlight the Untitled volume shown in the sidebar, then select the Restore button. For Restore from:, select the Projects volume, as shown below.

Finally, select the Restore button in the popup window. When finished, select the Done button. I needed to quit and open the Disk Utility to see the results. There should now be two Projects volumes, as shown below.


Highlight the first Projects volume shown in the sidebar, then select the Partition button. If necessary, select the Partition button in the popup window. With the partition containing the original Projects volume highlighted in the pie chart, select the - button. The result is shown below.

Next, select the Apply button, then the Partition button. When finished, select the Done button. I quit and opened the Disk Utility to be sure I was seeing the correct results. There should now be one Projects volume, as shown below.



You are finished.
Instructions When Projects Volume Is Formatted Mac OS Extended (Journaled)

Since your Projects Volume is APFS formatted, you can ignore the instructions below.

Before proceeding with the numbered steps given above, first execute the following instructions. Click on the Disk Utility window and then press the ⌘+2 key combination to insure the proper sidebar is displayed, as shown below.

Note: Your container numbering may different.


Next, highlight the container for the Untitled volume shown in the sidebar, then select the Erase button. For Format:, select the Mac OS Extended (Journaled), as shown below.

Finally, select the Erase button in the popup window. When finished, select the Done button. I needed to quit and open the Disk Utility to see the results. The Untitled volume should no longer be in a container, as shown below.

You can now proceed with the numbered steps given above.