The drawing area of lepton-schematic is large enough and the users should
have representation of logical extents of the schematics they are
working on. Title block symbol just aims to graphically define the
bounds of a created schematic page.
Title boxes are usually locked in order to prevent the user from selecting it accidentally and deleting along with other objects. Moreover, an unlocked title block would be confusingly selected instead of other objects within it every now and then. A title block symbol is inserted any time the user creates a new schematic. Since it is not needed in symbols, you may want to delete it just after new page creation. How to achieve that if you cannot select it? Just use box selection (see Box selection), left-click and drag the selection box to enclose the title block. Then use the usual deletion procedure: hit Delete or D.
What to do if you want to change it after adding some contents to your schematic page? Well, there are some tricks. First, you can just select all page contents excluding locked objects and move it to another place, then delete the title block as above. Another way, if the gEDA/gaf File Format Document is used, is just deleting title block definition in the schematic file itself. It is usually second and third lines of the file (the first one is the version specification).
For historical reasons, the default title block symbol is title-B.sym. In order to set up another symbol as default title block, change the default-titleblock configuration key. Choose the symbol you think will be used most often, and fix your user configuration. You may want to do so for some project if only it needs other title blocks. Amend your project configuration in such a case.
Note: If you misspelled title block symbol name in your configuration setting, or if the libraries linked in your project miss the symbol with the name, or there is no symbol with specified system default name when you did not changed the name in your local project configuration, new untitled pages will be created empty, without any title block. See the log if in doubt (Logging). See Missing symbols for how to check that symbol has not been found.
There are several predefined title block symbols in lepton-schematic. Open
the Add Component dialog box (see Add Component widget) and enter
title in the filter entry to find them.