On-demand local modification of high-$T_\text{c}$ superconductivity in few unit-cell thick Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$

High-temperature superconductors (HTS) are important for potential applications and for understanding the origin of strong correlations. Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (BSCCO), a van der Waals material, offers a platform to probe the physics down to a unit-cell. Guiding the flow of electrons by patterning 2DEGS and oxide heterostructures has brought new functionality and access to new science. Similarly, modifying superconductivity in HTS locally, on a small length scale, will be of immense interest for superconducting electronics. Here we report transport studies on few unit-cell thick BSCCO and modify its superconductivity locally by depositing metal on the surface. Deposition of chromium (Cr) on the surface over a selected area of BSCCO results in insulating behavior of the patterned region. Cr locally depletes oxygen in CuO$_2$ planes and disrupts the superconductivity in the layers below. Our technique of modifying superconductivity is suitable for making sub-micron superconducting wires and more complex superconducting electronic devices.