Citroen C4 Picasso Insufficient Memory for update

Trying to update 2015 Citroen C4 Picasso SMEG . Have updated some maps ok , but now I am getting Insufficient Memory message to proceed further .
Am I doing something wrong ? Anyone else had this problem ?
Is there any way to delete maps and then re-install new versions ?

Thanx for any suggestions .

Known problem, memory is too weak and maps are getting bigger.
Also, during update, system keeps the old map until the end of the process.
If there is no such space on SD card, system suggests to delete a map.
So, delete one map, the bigger one, and update maps one by one.

Thanks mytheuzen

Have done as suggested and now down to 1 map . However , map too big for remaining memory and I´m not being given the option to delete a database .
Is there a way to delete databases that is not documented anywhere ?

Ta much