Go to the Home screen, open the default PST file and select the items which you want to move to a new PST file you created. For this, click on the Move button from the top and select Copy to Folder option. Next, choose the PST file from the copy the selected items to the folder option and click OK.

Regards,
Peter

If you are looking for Free Split PST Tool then let me tell you something. After listening to which you will change your decision. Because there are many free tools available in the market. But if you have important data then a free tool is not best because while splitting the free tool some data of your file work with it which you don't want. So you should use a third-party tool that will keep your data safe and will not miss any data. If you want the same, then I have used a tool that proved to be good for my work. You can also use that tool if you want. ToolsBaer Outlook PST Split Tool makes this splitting process easy. Which also gives you 100% security. We can split our PST file in many ways in this software. Splits PST data in a few easy clicks. Let me tell you three more ways to partition this tool, such as partition by size, partition by folder, and partition by year. There is also a free demo of the tool.

Read More: https://www.toolsbaer.com/pst-split/

If you want to reduce OST file Size then, I want to suggest you Download SysInspire OST to PST Converter Software. With this software, you can reduce your File size with one click. It has many features that can help you to Convert OST to PST within one click such as OST to Office 365, HTML, EML, EMLX, and 10+ other file formats. It has a Split open which is a great feature in this feature you can split your PST Files into Multiples Blocks and also reduces the file size without Losing data.

Know more:- Free Spllit PST