If you need to clear space in your mailbox, it is not at all necessary to delete existing letters. The point is, there is another way: you can simply archive them.
All stages of this procedure can be disassembled using the example of Gmail. First, log in to the system (enter your username and password). Then go to your inbox. Check the box next to the message you want to move. Above the list of all emails, you will see a toolbar. On it, click on the "Archive" button. By the way, if you want to archive a message that is currently open, then you do not need to go to the general list: just click on the button above the message itself. Note that archiving only means moving to the All Mail folder, not deleting.
To view archived messages, follow the All Mail link (located on the left side of the page). You can then easily find such a letter thanks to the search function or the label assigned to it.
Don't be surprised if, after a while, the message you archived appears in your Inbox again. The reason may be that it received a response, and therefore the chain began to be displayed again.
As already mentioned, such messages are transferred to the "All letters" folder. However, its volume is also limited, as is the volume of an e-mail box. Therefore, you can store letters there for a long time, but not all. If it turns out to be overloaded, then something will still have to be erased. To do this, open the desired message, check the box next to it, and then click "Delete". Thus, you get rid of the entire chain of letters at once.
In addition, you can delete an individual message. To complete this procedure, you must open the conversation and select the one you want there. You will see a down arrow next to the Reply button. HE is located in the upper right corner of the special panel. To complete, click on the "Delete this message" column.